diff --git a/CHANGES.rst b/CHANGES.rst index 5d28c9e5..fed62257 100644 --- a/CHANGES.rst +++ b/CHANGES.rst @@ -5,6 +5,10 @@ Unreleased - Drop support for Python 3.9. :pr:`5730` - Remove previously deprecated code: ``__version__``. :pr:`5648` +- ``RequestContext`` has merged with ``AppContext``. ``RequestContext`` is now + a deprecated alias. If an app context is already pushed, it is not reused + when dispatching a request. This greatly simplifies the internal code for tracking + the active context. :issue:`5639` - ``template_filter``, ``template_test``, and ``template_global`` decorators can be used without parentheses. :issue:`5729` diff --git a/docs/api.rst b/docs/api.rst index 1aa8048f..d3c517f1 100644 --- a/docs/api.rst +++ b/docs/api.rst @@ -31,17 +31,15 @@ Incoming Request Data :inherited-members: :exclude-members: json_module -.. attribute:: request +.. data:: request - To access incoming request data, you can use the global `request` - object. Flask parses incoming request data for you and gives you - access to it through that global object. Internally Flask makes - sure that you always get the correct data for the active thread if you - are in a multithreaded environment. + A proxy to the request data for the current request, an instance of + :class:`.Request`. - This is a proxy. See :ref:`notes-on-proxies` for more information. + This is only available when a :doc:`request context ` is + active. - The request object is an instance of a :class:`~flask.Request`. + This is a proxy. See :ref:`context-visibility` for more information. Response Objects @@ -62,40 +60,33 @@ does this is by using a signed cookie. The user can look at the session contents, but can't modify it unless they know the secret key, so make sure to set that to something complex and unguessable. -To access the current session you can use the :class:`session` object: +To access the current session you can use the :data:`.session` proxy. -.. class:: session +.. data:: session - The session object works pretty much like an ordinary dict, with the - difference that it keeps track of modifications. + A proxy to the session data for the current request, an instance of + :class:`.SessionMixin`. - This is a proxy. See :ref:`notes-on-proxies` for more information. + This is only available when a :doc:`request context ` is + active. - The following attributes are interesting: + This is a proxy. See :ref:`context-visibility` for more information. - .. attribute:: new + The session object works like a dict but tracks assignment and access to its + keys. It cannot track modifications to mutable values, you need to set + :attr:`~.SessionMixin.modified` manually when modifying a list, dict, etc. - ``True`` if the session is new, ``False`` otherwise. + .. code-block:: python - .. attribute:: modified - - ``True`` if the session object detected a modification. Be advised - that modifications on mutable structures are not picked up - automatically, in that situation you have to explicitly set the - attribute to ``True`` yourself. Here an example:: - - # this change is not picked up because a mutable object (here - # a list) is changed. - session['objects'].append(42) + # appending to a list is not detected + session["numbers"].append(42) # so mark it as modified yourself session.modified = True - .. attribute:: permanent - - If set to ``True`` the session lives for - :attr:`~flask.Flask.permanent_session_lifetime` seconds. The - default is 31 days. If set to ``False`` (which is the default) the - session will be deleted when the user closes the browser. + The session is persisted across requests using a cookie. By default the + users's browser will clear the cookie when it is closed. Set + :attr:`~.SessionMixin.permanent` to ``True`` to persist the cookie for + :data:`PERMANENT_SESSION_LIFETIME`. Session Interface @@ -158,20 +149,21 @@ another, a global variable is not good enough because it would break in threaded environments. Flask provides you with a special object that ensures it is only valid for the active request and that will return different values for each request. In a nutshell: it does the right -thing, like it does for :class:`request` and :class:`session`. +thing, like it does for :data:`.request` and :data:`.session`. .. data:: g - A namespace object that can store data during an - :doc:`application context `. This is an instance of - :attr:`Flask.app_ctx_globals_class`, which defaults to - :class:`ctx._AppCtxGlobals`. + A proxy to a namespace object used to store data during a single request or + app context. An instance of :attr:`.Flask.app_ctx_globals_class`, which + defaults to :class:`._AppCtxGlobals`. - This is a good place to store resources during a request. For - example, a ``before_request`` function could load a user object from - a session id, then set ``g.user`` to be used in the view function. + This is a good place to store resources during a request. For example, a + :meth:`~.Flask.before_request` function could load a user object from a + session id, then set ``g.user`` to be used in the view function. - This is a proxy. See :ref:`notes-on-proxies` for more information. + This is only available when an :doc:`app context ` is active. + + This is a proxy. See :ref:`context-visibility` for more information. .. versionchanged:: 0.10 Bound to the application context instead of the request context. @@ -185,17 +177,16 @@ Useful Functions and Classes .. data:: current_app - A proxy to the application handling the current request. This is - useful to access the application without needing to import it, or if - it can't be imported, such as when using the application factory - pattern or in blueprints and extensions. + A proxy to the :class:`.Flask` application handling the current request or + other activity. - This is only available when an - :doc:`application context ` is pushed. This happens - automatically during requests and CLI commands. It can be controlled - manually with :meth:`~flask.Flask.app_context`. + This is useful to access the application without needing to import it, or if + it can't be imported, such as when using the application factory pattern or + in blueprints and extensions. - This is a proxy. See :ref:`notes-on-proxies` for more information. + This is only available when an :doc:`app context ` is active. + + This is a proxy. See :ref:`context-visibility` for more information. .. autofunction:: has_request_context @@ -299,31 +290,31 @@ Stream Helpers Useful Internals ---------------- -.. autoclass:: flask.ctx.RequestContext - :members: - -.. data:: flask.globals.request_ctx - - The current :class:`~flask.ctx.RequestContext`. If a request context - is not active, accessing attributes on this proxy will raise a - ``RuntimeError``. - - This is an internal object that is essential to how Flask handles - requests. Accessing this should not be needed in most cases. Most - likely you want :data:`request` and :data:`session` instead. - .. autoclass:: flask.ctx.AppContext :members: .. data:: flask.globals.app_ctx - The current :class:`~flask.ctx.AppContext`. If an app context is not - active, accessing attributes on this proxy will raise a - ``RuntimeError``. + A proxy to the active :class:`.AppContext`. - This is an internal object that is essential to how Flask handles - requests. Accessing this should not be needed in most cases. Most - likely you want :data:`current_app` and :data:`g` instead. + This is an internal object that is essential to how Flask handles requests. + Accessing this should not be needed in most cases. Most likely you want + :data:`.current_app`, :data:`.g`, :data:`.request`, and :data:`.session` instead. + + This is only available when a :doc:`request context ` is + active. + + This is a proxy. See :ref:`context-visibility` for more information. + +.. class:: flask.ctx.RequestContext + + .. deprecated:: 3.2 + Merged with :class:`AppContext`. This alias will be removed in Flask 4.0. + +.. data:: flask.globals.request_ctx + + .. deprecated:: 3.2 + Merged with :data:`.app_ctx`. This alias will be removed in Flask 4.0. .. autoclass:: flask.blueprints.BlueprintSetupState :members: diff --git a/docs/appcontext.rst b/docs/appcontext.rst index 5509a9a7..f05468f5 100644 --- a/docs/appcontext.rst +++ b/docs/appcontext.rst @@ -1,74 +1,63 @@ -.. currentmodule:: flask +The App and Request Context +=========================== -The Application Context -======================= +The context keeps track of data and objects during a request, CLI command, or +other activity. Rather than passing this data around to every function, the +:data:`.current_app`, :data:`.g`, :data:`.request`, and :data:`.session` proxies +are accessed instead. -The application context keeps track of the application-level data during -a request, CLI command, or other activity. Rather than passing the -application around to each function, the :data:`current_app` and -:data:`g` proxies are accessed instead. +When handling a request, the context is referred to as the "request context" +because it contains request data in addition to application data. Otherwise, +such as during a CLI command, it is referred to as the "app context". During an +app context, :data:`.current_app` and :data:`.g` are available, while during a +request context :data:`.request` and :data:`.session` are also available. -This is similar to :doc:`/reqcontext`, which keeps track of -request-level data during a request. A corresponding application context -is pushed when a request context is pushed. Purpose of the Context ---------------------- -The :class:`Flask` application object has attributes, such as -:attr:`~Flask.config`, that are useful to access within views and -:doc:`CLI commands `. However, importing the ``app`` instance -within the modules in your project is prone to circular import issues. -When using the :doc:`app factory pattern ` or -writing reusable :doc:`blueprints ` or -:doc:`extensions ` there won't be an ``app`` instance to -import at all. +The context and proxies help solve two development issues: circular imports, and +passing around global data during a request. -Flask solves this issue with the *application context*. Rather than -referring to an ``app`` directly, you use the :data:`current_app` -proxy, which points to the application handling the current activity. +The :class:`.Flask` application object has attributes, such as +:attr:`~.Flask.config`, that are useful to access within views and other +functions. However, importing the ``app`` instance within the modules in your +project is prone to circular import issues. When using the +:doc:`app factory pattern ` or writing reusable +:doc:`blueprints ` or :doc:`extensions ` there won't +be an ``app`` instance to import at all. -Flask automatically *pushes* an application context when handling a -request. View functions, error handlers, and other functions that run -during a request will have access to :data:`current_app`. +When the application handles a request, it creates a :class:`.Request` object. +Because a *worker* handles only one request at a time, the request data can be +considered global to that worker during that request. Passing it as an argument +through every function during the request becomes verbose and redundant. -Flask will also automatically push an app context when running CLI -commands registered with :attr:`Flask.cli` using ``@app.cli.command()``. +Flask solves these issues with the *active context* pattern. Rather than +importing an ``app`` directly, or having to pass it and the request through to +every single function, you import and access the proxies, which point to the +currently active application and request data. This is sometimes referred to +as "context local" data. -Lifetime of the Context ------------------------ +Context During Setup +-------------------- -The application context is created and destroyed as necessary. When a -Flask application begins handling a request, it pushes an application -context and a :doc:`request context `. When the request -ends it pops the request context then the application context. -Typically, an application context will have the same lifetime as a -request. - -See :doc:`/reqcontext` for more information about how the contexts work -and the full life cycle of a request. - - -Manually Push a Context ------------------------ - -If you try to access :data:`current_app`, or anything that uses it, -outside an application context, you'll get this error message: +If you try to access :data:`.current_app`, :data:`.g`, or anything that uses it, +outside an app context, you'll get this error message: .. code-block:: pytb RuntimeError: Working outside of application context. - This typically means that you attempted to use functionality that - needed to interface with the current application object in some way. - To solve this, set up an application context with app.app_context(). + Attempted to use functionality that expected a current application to be + set. To solve this, set up an app context using 'with app.app_context()'. + See the documentation on app context for more information. If you see that error while configuring your application, such as when -initializing an extension, you can push a context manually since you -have direct access to the ``app``. Use :meth:`~Flask.app_context` in a -``with`` block, and everything that runs in the block will have access -to :data:`current_app`. :: +initializing an extension, you can push a context manually since you have direct +access to the ``app``. Use :meth:`.Flask.app_context` in a ``with`` block. + +.. code-block:: python def create_app(): app = Flask(__name__) @@ -78,70 +67,120 @@ to :data:`current_app`. :: return app -If you see that error somewhere else in your code not related to -configuring the application, it most likely indicates that you should -move that code into a view function or CLI command. +If you see that error somewhere else in your code not related to setting up the +application, it most likely indicates that you should move that code into a view +function or CLI command. -Storing Data ------------- +Context During Testing +---------------------- -The application context is a good place to store common data during a -request or CLI command. Flask provides the :data:`g object ` for this -purpose. It is a simple namespace object that has the same lifetime as -an application context. +See :doc:`/testing` for detailed information about managing the context during +tests. -.. note:: - The ``g`` name stands for "global", but that is referring to the - data being global *within a context*. The data on ``g`` is lost - after the context ends, and it is not an appropriate place to store - data between requests. Use the :data:`session` or a database to - store data across requests. +If you try to access :data:`.request`, :data:`.session`, or anything that uses +it, outside a request context, you'll get this error message: -A common use for :data:`g` is to manage resources during a request. +.. code-block:: pytb -1. ``get_X()`` creates resource ``X`` if it does not exist, caching it - as ``g.X``. -2. ``teardown_X()`` closes or otherwise deallocates the resource if it - exists. It is registered as a :meth:`~Flask.teardown_appcontext` - handler. + RuntimeError: Working outside of request context. -For example, you can manage a database connection using this pattern:: + Attempted to use functionality that expected an active HTTP request. See the + documentation on request context for more information. - from flask import g +This will probably only happen during tests. If you see that error somewhere +else in your code not related to testing, it most likely indicates that you +should move that code into a view function. - def get_db(): - if 'db' not in g: - g.db = connect_to_database() +The primary way to solve this is to use :meth:`.Flask.test_client` to simulate +a full request. - return g.db +If you only want to unit test one function, rather than a full request, use +:meth:`.Flask.test_request_context` in a ``with`` block. - @app.teardown_appcontext - def teardown_db(exception): - db = g.pop('db', None) +.. code-block:: python - if db is not None: - db.close() + def generate_report(year): + format = request.args.get("format") + ... -During a request, every call to ``get_db()`` will return the same -connection, and it will be closed automatically at the end of the -request. - -You can use :class:`~werkzeug.local.LocalProxy` to make a new context -local from ``get_db()``:: - - from werkzeug.local import LocalProxy - db = LocalProxy(get_db) - -Accessing ``db`` will call ``get_db`` internally, in the same way that -:data:`current_app` works. + with app.test_request_context( + "/make_report/2017", query_string={"format": "short"} + ): + generate_report() -Events and Signals ------------------- +.. _context-visibility: -The application will call functions registered with :meth:`~Flask.teardown_appcontext` -when the application context is popped. +Visibility of the Context +------------------------- -The following signals are sent: :data:`appcontext_pushed`, -:data:`appcontext_tearing_down`, and :data:`appcontext_popped`. +The context will have the same lifetime as an activity, such as a request, CLI +command, or ``with`` block. Various callbacks and signals registered with the +app will be run during the context. + +When a Flask application handles a request, it pushes a requet context +to set the active application and request data. When it handles a CLI command, +it pushes an app context to set the active application. When the activity ends, +it pops that context. Proxy objects like :data:`.request`, :data:`.session`, +:data:`.g`, and :data:`.current_app`, are accessible while the context is pushed +and active, and are not accessible after the context is popped. + +The context is unique to each thread (or other worker type). The proxies cannot +be passed to another worker, which has a different context space and will not +know about the active context in the parent's space. + +Besides being scoped to each worker, the proxy object has a separate type and +identity than the proxied real object. In some cases you'll need access to the +real object, rather than the proxy. Use the +:meth:`~.LocalProxy._get_current_object` method in those cases. + +.. code-block:: python + + app = current_app._get_current_object() + my_signal.send(app) + + +Lifcycle of the Context +----------------------- + +Flask dispatches a request in multiple stages which can affect the request, +response, and how errors are handled. See :doc:`/lifecycle` for a list of all +the steps, callbacks, and signals during each request. The following are the +steps directly related to the context. + +- The app context is pushed, the proxies are available. +- The :data:`.appcontext_pushed` signal is sent. +- The request is dispatched. +- Any :meth:`.Flask.teardown_request` decorated functions are called. +- The :data:`.request_tearing_down` signal is sent. +- Any :meth:`.Flask.teardown_appcontext` decorated functions are called. +- The :data:`.appcontext_tearing_down` signal is sent. +- The app context is popped, the proxies are no longer available. +- The :data:`.appcontext_popped` signal is sent. + +The teardown callbacks are called by the context when it is popped. They are +called even if there is an unhandled exception during dispatch. They may be +called multiple times in some test scenarios. This means there is no guarantee +that any other parts of the request dispatch have run. Be sure to write these +functions in a way that does not depend on other callbacks and will not fail. + + +How the Context Works +--------------------- + +Context locals are implemented using Python's :mod:`contextvars` and Werkzeug's +:class:`~werkzeug.local.LocalProxy`. Python's contextvars are a low level +structure to manage data local to a thread or coroutine. ``LocalProxy`` wraps +the contextvar so that access to any attributes and methods is forwarded to the +object stored in the contextvar. + +The context is tracked like a stack, with the active context at the top of the +stack. Flask manages pushing and popping contexts during requests, CLI commands, +testing, ``with`` blocks, etc. The proxies access attributes on the active +context. + +Because it is a stack, other contexts may be pushed to change the proxies during +an already active context. This is not a common pattern, but can be used in +advanced use cases. For example, a Flask application can be used as WSGI +middleware, calling another wrapped Flask app from a view. diff --git a/docs/design.rst b/docs/design.rst index d3778b44..063f55ad 100644 --- a/docs/design.rst +++ b/docs/design.rst @@ -169,19 +169,20 @@ infrastructure, packages with dependencies are no longer an issue and there are very few reasons against having libraries that depend on others. -Thread Locals -------------- +Context Locals +-------------- -Flask uses thread local objects (context local objects in fact, they -support greenlet contexts as well) for request, session and an extra -object you can put your own things on (:data:`~flask.g`). Why is that and -isn't that a bad idea? +Flask uses special context locals and proxies to provide access to the +current app and request data to any code running during a request, CLI command, +etc. Context locals are specific to the worker handling the activity, such as a +thread, process, coroutine, or greenlet. -Yes it is usually not such a bright idea to use thread locals. They cause -troubles for servers that are not based on the concept of threads and make -large applications harder to maintain. However Flask is just not designed -for large applications or asynchronous servers. Flask wants to make it -quick and easy to write a traditional web application. +The context and proxies help solve two development issues: circular imports, and +passing around global data. :data:`.current_app: can be used to access the +application object without needing to import the app object directly, avoiding +circular import issues. :data:`.request`, :data:`.session`, and :data`.g` can be +imported to access the current data for the request, rather than needing to +pass them as arguments through every single function in your project. Async/await and ASGI support diff --git a/docs/extensiondev.rst b/docs/extensiondev.rst index c397d06b..ae5ed330 100644 --- a/docs/extensiondev.rst +++ b/docs/extensiondev.rst @@ -67,7 +67,7 @@ application instance. It is important that the app is not stored on the extension, don't do ``self.app = app``. The only time the extension should have direct access to an app is during ``init_app``, otherwise it should use -:data:`current_app`. +:data:`.current_app`. This allows the extension to support the application factory pattern, avoids circular import issues when importing the extension instance @@ -105,7 +105,7 @@ during an extension's ``init_app`` method. A common pattern is to use :meth:`~Flask.before_request` to initialize some data or a connection at the beginning of each request, then :meth:`~Flask.teardown_request` to clean it up at the end. This can be -stored on :data:`g`, discussed more below. +stored on :data:`.g`, discussed more below. A more lazy approach is to provide a method that initializes and caches the data or connection. For example, a ``ext.get_db`` method could @@ -179,13 +179,12 @@ name as a prefix, or as a namespace. g._hello = SimpleNamespace() g._hello.user_id = 2 -The data in ``g`` lasts for an application context. An application -context is active when a request context is, or when a CLI command is -run. If you're storing something that should be closed, use -:meth:`~flask.Flask.teardown_appcontext` to ensure that it gets closed -when the application context ends. If it should only be valid during a -request, or would not be used in the CLI outside a request, use -:meth:`~flask.Flask.teardown_request`. +The data in ``g`` lasts for an application context. An application context is +active during a request, CLI command, or ``with app.app_context()`` block. If +you're storing something that should be closed, use +:meth:`~flask.Flask.teardown_appcontext` to ensure that it gets closed when the +app context ends. If it should only be valid during a request, or would not be +used in the CLI outside a request, use :meth:`~flask.Flask.teardown_request`. Views and Models diff --git a/docs/index.rst b/docs/index.rst index 161085a7..63fdb866 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -52,7 +52,6 @@ community-maintained extensions to add even more functionality. views lifecycle appcontext - reqcontext blueprints extensions cli diff --git a/docs/lifecycle.rst b/docs/lifecycle.rst index 2344d98a..37d45cd9 100644 --- a/docs/lifecycle.rst +++ b/docs/lifecycle.rst @@ -117,15 +117,12 @@ the view function, and pass the return value back to the server. But there are m parts that you can use to customize its behavior. #. WSGI server calls the Flask object, which calls :meth:`.Flask.wsgi_app`. -#. A :class:`.RequestContext` object is created. This converts the WSGI ``environ`` - dict into a :class:`.Request` object. It also creates an :class:`AppContext` object. -#. The :doc:`app context ` is pushed, which makes :data:`.current_app` and - :data:`.g` available. +#. An :class:`.AppContext` object is created. This converts the WSGI ``environ`` + dict into a :class:`.Request` object. +#. The :doc:`app context ` is pushed, which makes + :data:`.current_app`, :data:`.g`, :data:`.request`, and :data:`.session` + available. #. The :data:`.appcontext_pushed` signal is sent. -#. The :doc:`request context ` is pushed, which makes :attr:`.request` and - :class:`.session` available. -#. The session is opened, loading any existing session data using the app's - :attr:`~.Flask.session_interface`, an instance of :class:`.SessionInterface`. #. The URL is matched against the URL rules registered with the :meth:`~.Flask.route` decorator during application setup. If there is no match, the error - usually a 404, 405, or redirect - is stored to be handled later. @@ -141,7 +138,8 @@ parts that you can use to customize its behavior. called to handle the error and return a response. #. Whatever returned a response value - a before request function, the view, or an error handler, that value is converted to a :class:`.Response` object. -#. Any :func:`~.after_this_request` decorated functions are called, then cleared. +#. Any :func:`~.after_this_request` decorated functions are called, which can modify + the response object. They are then cleared. #. Any :meth:`~.Flask.after_request` decorated functions are called, which can modify the response object. #. The session is saved, persisting any modified session data using the app's @@ -154,14 +152,19 @@ parts that you can use to customize its behavior. #. The response object's status, headers, and body are returned to the WSGI server. #. Any :meth:`~.Flask.teardown_request` decorated functions are called. #. The :data:`.request_tearing_down` signal is sent. -#. The request context is popped, :attr:`.request` and :class:`.session` are no longer - available. #. Any :meth:`~.Flask.teardown_appcontext` decorated functions are called. #. The :data:`.appcontext_tearing_down` signal is sent. -#. The app context is popped, :data:`.current_app` and :data:`.g` are no longer - available. +#. The app context is popped, :data:`.current_app`, :data:`.g`, :data:`.request`, + and :data:`.session` are no longer available. #. The :data:`.appcontext_popped` signal is sent. +When executing a CLI command or plain app context without request data, the same +order of steps is followed, omitting the steps that refer to the request. + +A :class:`Blueprint` can add handlers for these events that are specific to the +blueprint. The handlers for a blueprint will run if the blueprint +owns the route that matches the request. + There are even more decorators and customization points than this, but that aren't part of every request lifecycle. They're more specific to certain things you might use during a request, such as templates, building URLs, or handling JSON data. See the rest of this diff --git a/docs/patterns/sqlalchemy.rst b/docs/patterns/sqlalchemy.rst index 7e4108d0..9e9afe48 100644 --- a/docs/patterns/sqlalchemy.rst +++ b/docs/patterns/sqlalchemy.rst @@ -131,9 +131,8 @@ Here is an example :file:`database.py` module for your application:: def init_db(): metadata.create_all(bind=engine) -As in the declarative approach, you need to close the session after -each request or application context shutdown. Put this into your -application module:: +As in the declarative approach, you need to close the session after each app +context. Put this into your application module:: from yourapplication.database import db_session diff --git a/docs/patterns/sqlite3.rst b/docs/patterns/sqlite3.rst index 5932589f..f42e0f8e 100644 --- a/docs/patterns/sqlite3.rst +++ b/docs/patterns/sqlite3.rst @@ -1,9 +1,9 @@ Using SQLite 3 with Flask ========================= -In Flask you can easily implement the opening of database connections on -demand and closing them when the context dies (usually at the end of the -request). +You can implement a few functions to work with a SQLite connection during a +request context. The connection is created the first time it's accessed, +reused on subsequent access, until it is closed when the request context ends. Here is a simple example of how you can use SQLite 3 with Flask:: diff --git a/docs/patterns/streaming.rst b/docs/patterns/streaming.rst index 9842899a..ff356310 100644 --- a/docs/patterns/streaming.rst +++ b/docs/patterns/streaming.rst @@ -49,13 +49,13 @@ the template. Streaming with Context ---------------------- -The :data:`~flask.request` will not be active while the generator is -running, because the view has already returned at that point. If you try -to access ``request``, you'll get a ``RuntimeError``. +The :data:`.request` proxy will not be active while the generator is +running, because the app has already returned control to the WSGI server at that +point. If you try to access ``request``, you'll get a ``RuntimeError``. If your generator function relies on data in ``request``, use the -:func:`~flask.stream_with_context` wrapper. This will keep the request -context active during the generator. +:func:`.stream_with_context` wrapper. This will keep the request context active +during the generator. .. code-block:: python diff --git a/docs/quickstart.rst b/docs/quickstart.rst index 16a0761d..6af09eb6 100644 --- a/docs/quickstart.rst +++ b/docs/quickstart.rst @@ -258,7 +258,7 @@ Why would you want to build URLs using the URL reversing function For example, here we use the :meth:`~flask.Flask.test_request_context` method to try out :func:`~flask.url_for`. :meth:`~flask.Flask.test_request_context` tells Flask to behave as though it's handling a request even while we use a -Python shell. See :ref:`context-locals`. +Python shell. See :doc:`/appcontext`. .. code-block:: python @@ -449,105 +449,58 @@ Here is a basic introduction to how the :class:`~markupsafe.Markup` class works: Accessing Request Data ---------------------- -For web applications it's crucial to react to the data a client sends to -the server. In Flask this information is provided by the global -:class:`~flask.request` object. If you have some experience with Python -you might be wondering how that object can be global and how Flask -manages to still be threadsafe. The answer is context locals: +For web applications it's crucial to react to the data a client sends to the +server. In Flask this information is provided by the global :data:`.request` +object, which is an instance of :class:`.Request`. This object has many +attributes and methods to work with the incoming request data, but here is a +broad overview. First it needs to be imported. - -.. _context-locals: - -Context Locals -`````````````` - -.. admonition:: Insider Information - - If you want to understand how that works and how you can implement - tests with context locals, read this section, otherwise just skip it. - -Certain objects in Flask are global objects, but not of the usual kind. -These objects are actually proxies to objects that are local to a specific -context. What a mouthful. But that is actually quite easy to understand. - -Imagine the context being the handling thread. A request comes in and the -web server decides to spawn a new thread (or something else, the -underlying object is capable of dealing with concurrency systems other -than threads). When Flask starts its internal request handling it -figures out that the current thread is the active context and binds the -current application and the WSGI environments to that context (thread). -It does that in an intelligent way so that one application can invoke another -application without breaking. - -So what does this mean to you? Basically you can completely ignore that -this is the case unless you are doing something like unit testing. You -will notice that code which depends on a request object will suddenly break -because there is no request object. The solution is creating a request -object yourself and binding it to the context. The easiest solution for -unit testing is to use the :meth:`~flask.Flask.test_request_context` -context manager. In combination with the ``with`` statement it will bind a -test request so that you can interact with it. Here is an example:: +.. code-block:: python from flask import request - with app.test_request_context('/hello', method='POST'): - # now you can do something with the request until the - # end of the with block, such as basic assertions: - assert request.path == '/hello' - assert request.method == 'POST' +If you have some experience with Python you might be wondering how that object +can be global when Flask handles multiple requests at a time. The answer is +that :data:`.request` is actually a proxy, pointing at whatever request is +currently being handled by a given worker, which is managed interanlly by Flask +and Python. See :doc:`/appcontext` for much more information. -The other possibility is passing a whole WSGI environment to the -:meth:`~flask.Flask.request_context` method:: +The current request method is available in the :attr:`~.Request.method` +attribute. To access form data (data transmitted in a ``POST`` or ``PUT`` +request), use the :attr:`~flask.Request.form` attribute, which behaves like a +dict. - with app.request_context(environ): - assert request.method == 'POST' +.. code-block:: python -The Request Object -`````````````````` - -The request object is documented in the API section and we will not cover -it here in detail (see :class:`~flask.Request`). Here is a broad overview of -some of the most common operations. First of all you have to import it from -the ``flask`` module:: - - from flask import request - -The current request method is available by using the -:attr:`~flask.Request.method` attribute. To access form data (data -transmitted in a ``POST`` or ``PUT`` request) you can use the -:attr:`~flask.Request.form` attribute. Here is a full example of the two -attributes mentioned above:: - - @app.route('/login', methods=['POST', 'GET']) + @app.route("/login", methods=["GET", "POST"]) def login(): error = None - if request.method == 'POST': - if valid_login(request.form['username'], - request.form['password']): - return log_the_user_in(request.form['username']) + + if request.method == "POST": + if valid_login(request.form["username"], request.form["password"]): + return store_login(request.form["username"]) else: - error = 'Invalid username/password' - # the code below is executed if the request method - # was GET or the credentials were invalid - return render_template('login.html', error=error) + error = "Invalid username or password" -What happens if the key does not exist in the ``form`` attribute? In that -case a special :exc:`KeyError` is raised. You can catch it like a -standard :exc:`KeyError` but if you don't do that, a HTTP 400 Bad Request -error page is shown instead. So for many situations you don't have to -deal with that problem. + # Executed if the request method was GET or the credentials were invalid. + return render_template("login.html", error=error) -To access parameters submitted in the URL (``?key=value``) you can use the -:attr:`~flask.Request.args` attribute:: +If the key does not exist in ``form``, a special :exc:`KeyError` is raised. You +can catch it like a normal ``KeyError``, otherwise it will return a HTTP 400 +Bad Request error page. You can also use the +:meth:`~werkzeug.datastructures.MultiDict.get` method to get a default +instead of an error. + +To access parameters submitted in the URL (``?key=value``), use the +:attr:`~.Request.args` attribute. Key errors behave the same as ``form``, +returning a 400 response if not caught. + +.. code-block:: python searchword = request.args.get('key', '') -We recommend accessing URL parameters with `get` or by catching the -:exc:`KeyError` because users might change the URL and presenting them a 400 -bad request page in that case is not user friendly. - -For a full list of methods and attributes of the request object, head over -to the :class:`~flask.Request` documentation. +For a full list of methods and attributes of the request object, see the +:class:`~.Request` documentation. File Uploads diff --git a/docs/reqcontext.rst b/docs/reqcontext.rst index 4f1846a3..6660671e 100644 --- a/docs/reqcontext.rst +++ b/docs/reqcontext.rst @@ -1,243 +1,6 @@ -.. currentmodule:: flask +:orphan: The Request Context =================== -The request context keeps track of the request-level data during a -request. Rather than passing the request object to each function that -runs during a request, the :data:`request` and :data:`session` proxies -are accessed instead. - -This is similar to :doc:`/appcontext`, which keeps track of the -application-level data independent of a request. A corresponding -application context is pushed when a request context is pushed. - - -Purpose of the Context ----------------------- - -When the :class:`Flask` application handles a request, it creates a -:class:`Request` object based on the environment it received from the -WSGI server. Because a *worker* (thread, process, or coroutine depending -on the server) handles only one request at a time, the request data can -be considered global to that worker during that request. Flask uses the -term *context local* for this. - -Flask automatically *pushes* a request context when handling a request. -View functions, error handlers, and other functions that run during a -request will have access to the :data:`request` proxy, which points to -the request object for the current request. - - -Lifetime of the Context ------------------------ - -When a Flask application begins handling a request, it pushes a request -context, which also pushes an :doc:`app context `. When the -request ends it pops the request context then the application context. - -The context is unique to each thread (or other worker type). -:data:`request` cannot be passed to another thread, the other thread has -a different context space and will not know about the request the parent -thread was pointing to. - -Context locals are implemented using Python's :mod:`contextvars` and -Werkzeug's :class:`~werkzeug.local.LocalProxy`. Python manages the -lifetime of context vars automatically, and local proxy wraps that -low-level interface to make the data easier to work with. - - -Manually Push a Context ------------------------ - -If you try to access :data:`request`, or anything that uses it, outside -a request context, you'll get this error message: - -.. code-block:: pytb - - RuntimeError: Working outside of request context. - - This typically means that you attempted to use functionality that - needed an active HTTP request. Consult the documentation on testing - for information about how to avoid this problem. - -This should typically only happen when testing code that expects an -active request. One option is to use the -:meth:`test client ` to simulate a full request. Or -you can use :meth:`~Flask.test_request_context` in a ``with`` block, and -everything that runs in the block will have access to :data:`request`, -populated with your test data. :: - - def generate_report(year): - format = request.args.get("format") - ... - - with app.test_request_context( - "/make_report/2017", query_string={"format": "short"} - ): - generate_report() - -If you see that error somewhere else in your code not related to -testing, it most likely indicates that you should move that code into a -view function. - -For information on how to use the request context from the interactive -Python shell, see :doc:`/shell`. - - -How the Context Works ---------------------- - -The :meth:`Flask.wsgi_app` method is called to handle each request. It -manages the contexts during the request. Internally, the request and -application contexts work like stacks. When contexts are pushed, the -proxies that depend on them are available and point at information from -the top item. - -When the request starts, a :class:`~ctx.RequestContext` is created and -pushed, which creates and pushes an :class:`~ctx.AppContext` first if -a context for that application is not already the top context. While -these contexts are pushed, the :data:`current_app`, :data:`g`, -:data:`request`, and :data:`session` proxies are available to the -original thread handling the request. - -Other contexts may be pushed to change the proxies during a request. -While this is not a common pattern, it can be used in advanced -applications to, for example, do internal redirects or chain different -applications together. - -After the request is dispatched and a response is generated and sent, -the request context is popped, which then pops the application context. -Immediately before they are popped, the :meth:`~Flask.teardown_request` -and :meth:`~Flask.teardown_appcontext` functions are executed. These -execute even if an unhandled exception occurred during dispatch. - - -.. _callbacks-and-errors: - -Callbacks and Errors --------------------- - -Flask dispatches a request in multiple stages which can affect the -request, response, and how errors are handled. The contexts are active -during all of these stages. - -A :class:`Blueprint` can add handlers for these events that are specific -to the blueprint. The handlers for a blueprint will run if the blueprint -owns the route that matches the request. - -#. Before each request, :meth:`~Flask.before_request` functions are - called. If one of these functions return a value, the other - functions are skipped. The return value is treated as the response - and the view function is not called. - -#. If the :meth:`~Flask.before_request` functions did not return a - response, the view function for the matched route is called and - returns a response. - -#. The return value of the view is converted into an actual response - object and passed to the :meth:`~Flask.after_request` - functions. Each function returns a modified or new response object. - -#. After the response is returned, the contexts are popped, which calls - the :meth:`~Flask.teardown_request` and - :meth:`~Flask.teardown_appcontext` functions. These functions are - called even if an unhandled exception was raised at any point above. - -If an exception is raised before the teardown functions, Flask tries to -match it with an :meth:`~Flask.errorhandler` function to handle the -exception and return a response. If no error handler is found, or the -handler itself raises an exception, Flask returns a generic -``500 Internal Server Error`` response. The teardown functions are still -called, and are passed the exception object. - -If debug mode is enabled, unhandled exceptions are not converted to a -``500`` response and instead are propagated to the WSGI server. This -allows the development server to present the interactive debugger with -the traceback. - - -Teardown Callbacks -~~~~~~~~~~~~~~~~~~ - -The teardown callbacks are independent of the request dispatch, and are -instead called by the contexts when they are popped. The functions are -called even if there is an unhandled exception during dispatch, and for -manually pushed contexts. This means there is no guarantee that any -other parts of the request dispatch have run first. Be sure to write -these functions in a way that does not depend on other callbacks and -will not fail. - -During testing, it can be useful to defer popping the contexts after the -request ends, so that their data can be accessed in the test function. -Use the :meth:`~Flask.test_client` as a ``with`` block to preserve the -contexts until the ``with`` block exits. - -.. code-block:: python - - from flask import Flask, request - - app = Flask(__name__) - - @app.route('/') - def hello(): - print('during view') - return 'Hello, World!' - - @app.teardown_request - def show_teardown(exception): - print('after with block') - - with app.test_request_context(): - print('during with block') - - # teardown functions are called after the context with block exits - - with app.test_client() as client: - client.get('/') - # the contexts are not popped even though the request ended - print(request.path) - - # the contexts are popped and teardown functions are called after - # the client with block exits - -Signals -~~~~~~~ - -The following signals are sent: - -#. :data:`request_started` is sent before the :meth:`~Flask.before_request` functions - are called. -#. :data:`request_finished` is sent after the :meth:`~Flask.after_request` functions - are called. -#. :data:`got_request_exception` is sent when an exception begins to be handled, but - before an :meth:`~Flask.errorhandler` is looked up or called. -#. :data:`request_tearing_down` is sent after the :meth:`~Flask.teardown_request` - functions are called. - - -.. _notes-on-proxies: - -Notes On Proxies ----------------- - -Some of the objects provided by Flask are proxies to other objects. The -proxies are accessed in the same way for each worker thread, but -point to the unique object bound to each worker behind the scenes as -described on this page. - -Most of the time you don't have to care about that, but there are some -exceptions where it is good to know that this object is actually a proxy: - -- The proxy objects cannot fake their type as the actual object types. - If you want to perform instance checks, you have to do that on the - object being proxied. -- The reference to the proxied object is needed in some situations, - such as sending :doc:`signals` or passing data to a background - thread. - -If you need to access the underlying object that is proxied, use the -:meth:`~werkzeug.local.LocalProxy._get_current_object` method:: - - app = current_app._get_current_object() - my_signal.send(app) +Obsolete, see :doc:`/appcontext` instead. diff --git a/docs/shell.rst b/docs/shell.rst index 7e42e285..d8821e23 100644 --- a/docs/shell.rst +++ b/docs/shell.rst @@ -1,56 +1,37 @@ Working with the Shell ====================== -.. versionadded:: 0.3 +One of the reasons everybody loves Python is the interactive shell. It allows +you to play around with code in real time and immediately get results back. +Flask provides the ``flask shell`` CLI command to start an interactive Python +shell with some setup done to make working with the Flask app easier. -One of the reasons everybody loves Python is the interactive shell. It -basically allows you to execute Python commands in real time and -immediately get results back. Flask itself does not come with an -interactive shell, because it does not require any specific setup upfront, -just import your application and start playing around. +.. code-block:: text -There are however some handy helpers to make playing around in the shell a -more pleasant experience. The main issue with interactive console -sessions is that you're not triggering a request like a browser does which -means that :data:`~flask.g`, :data:`~flask.request` and others are not -available. But the code you want to test might depend on them, so what -can you do? - -This is where some helper functions come in handy. Keep in mind however -that these functions are not only there for interactive shell usage, but -also for unit testing and other situations that require a faked request -context. - -Generally it's recommended that you read :doc:`reqcontext` first. - -Command Line Interface ----------------------- - -Starting with Flask 0.11 the recommended way to work with the shell is the -``flask shell`` command which does a lot of this automatically for you. -For instance the shell is automatically initialized with a loaded -application context. - -For more information see :doc:`/cli`. + $ flask shell Creating a Request Context -------------------------- +``flask shell`` pushes an app context automatically, so :data:`.current_app` and +:data:`.g` are already available. However, there is no HTTP request being +handled in the shell, so :data:`.request` and :data:`.session` are not yet +available. + The easiest way to create a proper request context from the shell is by using the :attr:`~flask.Flask.test_request_context` method which creates us a :class:`~flask.ctx.RequestContext`: >>> ctx = app.test_request_context() -Normally you would use the ``with`` statement to make this request object -active, but in the shell it's easier to use the -:meth:`~flask.ctx.RequestContext.push` and -:meth:`~flask.ctx.RequestContext.pop` methods by hand: +Normally you would use the ``with`` statement to make this context active, but +in the shell it's easier to call :meth:`~.RequestContext.push` and +:meth:`~.RequestContext.pop` manually: >>> ctx.push() -From that point onwards you can work with the request object until you -call `pop`: +From that point onwards you can work with the request object until you call +``pop``: >>> ctx.pop() diff --git a/docs/signals.rst b/docs/signals.rst index 739bb0b5..7ca81a9d 100644 --- a/docs/signals.rst +++ b/docs/signals.rst @@ -144,11 +144,10 @@ function, you can pass ``current_app._get_current_object()`` as sender. Signals and Flask's Request Context ----------------------------------- -Signals fully support :doc:`reqcontext` when receiving signals. -Context-local variables are consistently available between -:data:`~flask.request_started` and :data:`~flask.request_finished`, so you can -rely on :class:`flask.g` and others as needed. Note the limitations described -in :ref:`signals-sending` and the :data:`~flask.request_tearing_down` signal. +Context-local proxies are available between :data:`~flask.request_started` and +:data:`~flask.request_finished`, so you can rely on :class:`flask.g` and others +as needed. Note the limitations described in :ref:`signals-sending` and the +:data:`~flask.request_tearing_down` signal. Decorator Based Signal Subscriptions diff --git a/docs/testing.rst b/docs/testing.rst index b1d52f9a..c171abd6 100644 --- a/docs/testing.rst +++ b/docs/testing.rst @@ -275,11 +275,10 @@ command from the command line. Tests that depend on an Active Context -------------------------------------- -You may have functions that are called from views or commands, that -expect an active :doc:`application context ` or -:doc:`request context ` because they access ``request``, -``session``, or ``current_app``. Rather than testing them by making a -request or invoking the command, you can create and activate a context +You may have functions that are called from views or commands, that expect an +active :doc:`app context ` because they access :data:`.request`, +:data:`.session`, :data:`.g`, or :data:`.current_app`. Rather than testing them by +making a request or invoking the command, you can create and activate a context directly. Use ``with app.app_context()`` to push an application context. For diff --git a/docs/tutorial/blog.rst b/docs/tutorial/blog.rst index b06329ea..6418f5ff 100644 --- a/docs/tutorial/blog.rst +++ b/docs/tutorial/blog.rst @@ -305,7 +305,7 @@ The pattern ``{{ request.form['title'] or post['title'] }}`` is used to choose what data appears in the form. When the form hasn't been submitted, the original ``post`` data appears, but if invalid form data was posted you want to display that so the user can fix the error, so -``request.form`` is used instead. :data:`request` is another variable +``request.form`` is used instead. :data:`.request` is another variable that's automatically available in templates. diff --git a/docs/tutorial/database.rst b/docs/tutorial/database.rst index 93abf93a..cf132603 100644 --- a/docs/tutorial/database.rst +++ b/docs/tutorial/database.rst @@ -60,17 +60,17 @@ response is sent. if db is not None: db.close() -:data:`g` is a special object that is unique for each request. It is +:data:`.g` is a special object that is unique for each request. It is used to store data that might be accessed by multiple functions during the request. The connection is stored and reused instead of creating a new connection if ``get_db`` is called a second time in the same request. -:data:`current_app` is another special object that points to the Flask +:data:`.current_app` is another special object that points to the Flask application handling the request. Since you used an application factory, there is no application object when writing the rest of your code. ``get_db`` will be called when the application has been created and is -handling a request, so :data:`current_app` can be used. +handling a request, so :data:`.current_app` can be used. :func:`sqlite3.connect` establishes a connection to the file pointed at by the ``DATABASE`` configuration key. This file doesn't have to exist diff --git a/docs/tutorial/templates.rst b/docs/tutorial/templates.rst index 1a5535cc..ca9d4b32 100644 --- a/docs/tutorial/templates.rst +++ b/docs/tutorial/templates.rst @@ -71,7 +71,7 @@ specific sections. {% block content %}{% endblock %} -:data:`g` is automatically available in templates. Based on if +:data:`.g` is automatically available in templates. Based on if ``g.user`` is set (from ``load_logged_in_user``), either the username and a log out link are displayed, or links to register and log in are displayed. :func:`url_for` is also automatically available, and is diff --git a/docs/tutorial/tests.rst b/docs/tutorial/tests.rst index f4744cda..8958e773 100644 --- a/docs/tutorial/tests.rst +++ b/docs/tutorial/tests.rst @@ -311,7 +311,7 @@ input and error messages without writing the same code three times. The tests for the ``login`` view are very similar to those for ``register``. Rather than testing the data in the database, -:data:`session` should have ``user_id`` set after logging in. +:data:`.session` should have ``user_id`` set after logging in. .. code-block:: python :caption: ``tests/test_auth.py`` @@ -336,10 +336,10 @@ The tests for the ``login`` view are very similar to those for assert message in response.data Using ``client`` in a ``with`` block allows accessing context variables -such as :data:`session` after the response is returned. Normally, +such as :data:`.session` after the response is returned. Normally, accessing ``session`` outside of a request would raise an error. -Testing ``logout`` is the opposite of ``login``. :data:`session` should +Testing ``logout`` is the opposite of ``login``. :data:`.session` should not contain ``user_id`` after logging out. .. code-block:: python diff --git a/docs/tutorial/views.rst b/docs/tutorial/views.rst index 7092dbc2..6626628a 100644 --- a/docs/tutorial/views.rst +++ b/docs/tutorial/views.rst @@ -208,13 +208,13 @@ There are a few differences from the ``register`` view: password in the same way as the stored hash and securely compares them. If they match, the password is valid. -#. :data:`session` is a :class:`dict` that stores data across requests. +#. :data:`.session` is a :class:`dict` that stores data across requests. When validation succeeds, the user's ``id`` is stored in a new session. The data is stored in a *cookie* that is sent to the browser, and the browser then sends it back with subsequent requests. Flask securely *signs* the data so that it can't be tampered with. -Now that the user's ``id`` is stored in the :data:`session`, it will be +Now that the user's ``id`` is stored in the :data:`.session`, it will be available on subsequent requests. At the beginning of each request, if a user is logged in their information should be loaded and made available to other views. @@ -236,7 +236,7 @@ available to other views. :meth:`bp.before_app_request() ` registers a function that runs before the view function, no matter what URL is requested. ``load_logged_in_user`` checks if a user id is stored in the -:data:`session` and gets that user's data from the database, storing it +:data:`.session` and gets that user's data from the database, storing it on :data:`g.user `, which lasts for the length of the request. If there is no user id, or if the id doesn't exist, ``g.user`` will be ``None``. @@ -245,7 +245,7 @@ there is no user id, or if the id doesn't exist, ``g.user`` will be Logout ------ -To log out, you need to remove the user id from the :data:`session`. +To log out, you need to remove the user id from the :data:`.session`. Then ``load_logged_in_user`` won't load a user on subsequent requests. .. code-block:: python diff --git a/src/flask/app.py b/src/flask/app.py index 1232b03d..1149e248 100644 --- a/src/flask/app.py +++ b/src/flask/app.py @@ -29,20 +29,15 @@ from werkzeug.wsgi import get_host from . import cli from . import typing as ft from .ctx import AppContext -from .ctx import RequestContext from .globals import _cv_app -from .globals import _cv_request -from .globals import current_app from .globals import g from .globals import request -from .globals import request_ctx from .globals import session from .helpers import get_debug_flag from .helpers import get_flashed_messages from .helpers import get_load_dotenv from .helpers import send_from_directory from .sansio.app import App -from .sansio.scaffold import _sentinel from .sessions import SecureCookieSessionInterface from .sessions import SessionInterface from .signals import appcontext_tearing_down @@ -295,7 +290,7 @@ class Flask(App): .. versionadded:: 0.9 """ - value = current_app.config["SEND_FILE_MAX_AGE_DEFAULT"] + value = self.config["SEND_FILE_MAX_AGE_DEFAULT"] if value is None: return None @@ -517,8 +512,8 @@ class Flask(App): names: t.Iterable[str | None] = (None,) # A template may be rendered outside a request context. - if request: - names = chain(names, reversed(request.blueprints)) + if (ctx := _cv_app.get(None)) is not None and ctx.has_request: + names = chain(names, reversed(ctx.request.blueprints)) # The values passed to render_template take precedence. Keep a # copy to re-apply after all context functions. @@ -886,7 +881,8 @@ class Flask(App): This no longer does the exception handling, this code was moved to the new :meth:`full_dispatch_request`. """ - req = request_ctx.request + req = _cv_app.get().request + if req.routing_exception is not None: self.raise_routing_exception(req) rule: Rule = req.url_rule # type: ignore[assignment] @@ -957,7 +953,7 @@ class Flask(App): .. versionadded:: 0.7 """ - adapter = request_ctx.url_adapter + adapter = _cv_app.get().url_adapter methods = adapter.allowed_methods() # type: ignore[union-attr] rv = self.response_class() rv.allow.update(methods) @@ -1057,11 +1053,9 @@ class Flask(App): .. versionadded:: 2.2 Moved from ``flask.url_for``, which calls this method. """ - req_ctx = _cv_request.get(None) - - if req_ctx is not None: - url_adapter = req_ctx.url_adapter - blueprint_name = req_ctx.request.blueprint + if (ctx := _cv_app.get(None)) is not None and ctx.has_request: + url_adapter = ctx.url_adapter + blueprint_name = ctx.request.blueprint # If the endpoint starts with "." and the request matches a # blueprint, the endpoint is relative to the blueprint. @@ -1076,13 +1070,11 @@ class Flask(App): if _external is None: _external = _scheme is not None else: - app_ctx = _cv_app.get(None) - # If called by helpers.url_for, an app context is active, # use its url_adapter. Otherwise, app.url_for was called # directly, build an adapter. - if app_ctx is not None: - url_adapter = app_ctx.url_adapter + if ctx is not None: + url_adapter = ctx.url_adapter else: url_adapter = self.create_url_adapter(None) @@ -1278,12 +1270,13 @@ class Flask(App): value is handled as if it was the return value from the view, and further request handling is stopped. """ - names = (None, *reversed(request.blueprints)) + req = _cv_app.get().request + names = (None, *reversed(req.blueprints)) for name in names: if name in self.url_value_preprocessors: for url_func in self.url_value_preprocessors[name]: - url_func(request.endpoint, request.view_args) + url_func(req.endpoint, req.view_args) for name in names: if name in self.before_request_funcs: @@ -1308,12 +1301,12 @@ class Flask(App): :return: a new response object or the same, has to be an instance of :attr:`response_class`. """ - ctx = request_ctx._get_current_object() # type: ignore[attr-defined] + ctx = _cv_app.get() for func in ctx._after_request_functions: response = self.ensure_sync(func)(response) - for name in chain(request.blueprints, (None,)): + for name in chain(ctx.request.blueprints, (None,)): if name in self.after_request_funcs: for func in reversed(self.after_request_funcs[name]): response = self.ensure_sync(func)(response) @@ -1323,77 +1316,57 @@ class Flask(App): return response - def do_teardown_request( - self, - exc: BaseException | None = _sentinel, # type: ignore[assignment] - ) -> None: - """Called after the request is dispatched and the response is - returned, right before the request context is popped. + def do_teardown_request(self, exc: BaseException | None = None) -> None: + """Called after the request is dispatched and the response is finalized, + right before the request context is popped. Called by + :meth:`.AppContext.pop`. - This calls all functions decorated with - :meth:`teardown_request`, and :meth:`Blueprint.teardown_request` - if a blueprint handled the request. Finally, the - :data:`request_tearing_down` signal is sent. + This calls all functions decorated with :meth:`teardown_request`, and + :meth:`Blueprint.teardown_request` if a blueprint handled the request. + Finally, the :data:`request_tearing_down` signal is sent. - This is called by - :meth:`RequestContext.pop() `, - which may be delayed during testing to maintain access to - resources. - - :param exc: An unhandled exception raised while dispatching the - request. Detected from the current exception information if - not passed. Passed to each teardown function. + :param exc: An unhandled exception raised while dispatching the request. + Passed to each teardown function. .. versionchanged:: 0.9 Added the ``exc`` argument. """ - if exc is _sentinel: - exc = sys.exc_info()[1] + req = _cv_app.get().request - for name in chain(request.blueprints, (None,)): + for name in chain(req.blueprints, (None,)): if name in self.teardown_request_funcs: for func in reversed(self.teardown_request_funcs[name]): self.ensure_sync(func)(exc) request_tearing_down.send(self, _async_wrapper=self.ensure_sync, exc=exc) - def do_teardown_appcontext( - self, - exc: BaseException | None = _sentinel, # type: ignore[assignment] - ) -> None: - """Called right before the application context is popped. + def do_teardown_appcontext(self, exc: BaseException | None = None) -> None: + """Called right before the application context is popped. Called by + :meth:`.AppContext.pop`. - When handling a request, the application context is popped - after the request context. See :meth:`do_teardown_request`. + This calls all functions decorated with :meth:`teardown_appcontext`. + Then the :data:`appcontext_tearing_down` signal is sent. - This calls all functions decorated with - :meth:`teardown_appcontext`. Then the - :data:`appcontext_tearing_down` signal is sent. - - This is called by - :meth:`AppContext.pop() `. + :param exc: An unhandled exception raised while the context was active. + Passed to each teardown function. .. versionadded:: 0.9 """ - if exc is _sentinel: - exc = sys.exc_info()[1] - for func in reversed(self.teardown_appcontext_funcs): self.ensure_sync(func)(exc) appcontext_tearing_down.send(self, _async_wrapper=self.ensure_sync, exc=exc) def app_context(self) -> AppContext: - """Create an :class:`~flask.ctx.AppContext`. Use as a ``with`` - block to push the context, which will make :data:`current_app` - point at this application. + """Create an :class:`.AppContext`. When the context is pushed, + :data:`.current_app` and :data:`.g` become available. - An application context is automatically pushed by - :meth:`RequestContext.push() ` - when handling a request, and when running a CLI command. Use - this to manually create a context outside of these situations. + A context is automatically pushed when handling each request, and when + running any ``flask`` CLI command. Use this as a ``with`` block to + manually push a context outside of those situations, such as during + setup or testing. - :: + .. code-block:: python with app.app_context(): init_db() @@ -1404,44 +1377,37 @@ class Flask(App): """ return AppContext(self) - def request_context(self, environ: WSGIEnvironment) -> RequestContext: - """Create a :class:`~flask.ctx.RequestContext` representing a - WSGI environment. Use a ``with`` block to push the context, - which will make :data:`request` point at this request. + def request_context(self, environ: WSGIEnvironment) -> AppContext: + """Create an :class:`.AppContext` with request information representing + the given WSGI environment. A context is automatically pushed when + handling each request. When the context is pushed, :data:`.request`, + :data:`.session`, :data:`g:, and :data:`.current_app` become available. - See :doc:`/reqcontext`. + This method should not be used in your own code. Creating a valid WSGI + environ is not trivial. Use :meth:`test_request_context` to correctly + create a WSGI environ and request context instead. - Typically you should not call this from your own code. A request - context is automatically pushed by the :meth:`wsgi_app` when - handling a request. Use :meth:`test_request_context` to create - an environment and context instead of this method. + See :doc:`/appcontext`. - :param environ: a WSGI environment + :param environ: A WSGI environment. """ - return RequestContext(self, environ) + return AppContext.from_environ(self, environ) - def test_request_context(self, *args: t.Any, **kwargs: t.Any) -> RequestContext: - """Create a :class:`~flask.ctx.RequestContext` for a WSGI - environment created from the given values. This is mostly useful - during testing, where you may want to run a function that uses - request data without dispatching a full request. + def test_request_context(self, *args: t.Any, **kwargs: t.Any) -> AppContext: + """Create an :class:`.AppContext` with request information created from + the given arguments. When the context is pushed, :data:`.request`, + :data:`.session`, :data:`g:, and :data:`.current_app` become available. - See :doc:`/reqcontext`. + This is useful during testing to run a function that uses request data + without dispatching a full request. Use this as a ``with`` block to push + a context. - Use a ``with`` block to push the context, which will make - :data:`request` point at the request for the created - environment. :: + .. code-block:: python with app.test_request_context(...): generate_report() - When using the shell, it may be easier to push and pop the - context manually to avoid indentation. :: - - ctx = app.test_request_context(...) - ctx.push() - ... - ctx.pop() + See :doc:`/appcontext`. Takes the same arguments as Werkzeug's :class:`~werkzeug.test.EnvironBuilder`, with some defaults from @@ -1451,20 +1417,18 @@ class Flask(App): :param path: URL path being requested. :param base_url: Base URL where the app is being served, which ``path`` is relative to. If not given, built from - :data:`PREFERRED_URL_SCHEME`, ``subdomain``, - :data:`SERVER_NAME`, and :data:`APPLICATION_ROOT`. - :param subdomain: Subdomain name to append to - :data:`SERVER_NAME`. + :data:`PREFERRED_URL_SCHEME`, ``subdomain``, :data:`SERVER_NAME`, + and :data:`APPLICATION_ROOT`. + :param subdomain: Subdomain name to prepend to :data:`SERVER_NAME`. :param url_scheme: Scheme to use instead of :data:`PREFERRED_URL_SCHEME`. - :param data: The request body, either as a string or a dict of - form keys and values. + :param data: The request body text or bytes,or a dict of form data. :param json: If given, this is serialized as JSON and passed as ``data``. Also defaults ``content_type`` to ``application/json``. - :param args: other positional arguments passed to + :param args: Other positional arguments passed to :class:`~werkzeug.test.EnvironBuilder`. - :param kwargs: other keyword arguments passed to + :param kwargs: Other keyword arguments passed to :class:`~werkzeug.test.EnvironBuilder`. """ from .testing import EnvironBuilder @@ -1472,10 +1436,12 @@ class Flask(App): builder = EnvironBuilder(self, *args, **kwargs) try: - return self.request_context(builder.get_environ()) + environ = builder.get_environ() finally: builder.close() + return self.request_context(environ) + def wsgi_app( self, environ: WSGIEnvironment, start_response: StartResponse ) -> cabc.Iterable[bytes]: @@ -1496,7 +1462,6 @@ class Flask(App): Teardown events for the request and app contexts are called even if an unhandled error occurs. Other events may not be called depending on when an error occurs during dispatch. - See :ref:`callbacks-and-errors`. :param environ: A WSGI environment. :param start_response: A callable accepting a status code, @@ -1519,7 +1484,6 @@ class Flask(App): finally: if "werkzeug.debug.preserve_context" in environ: environ["werkzeug.debug.preserve_context"](_cv_app.get()) - environ["werkzeug.debug.preserve_context"](_cv_request.get()) if error is not None and self.should_ignore_error(error): error = None diff --git a/src/flask/cli.py b/src/flask/cli.py index 32a35f87..3fa65cfd 100644 --- a/src/flask/cli.py +++ b/src/flask/cli.py @@ -628,7 +628,7 @@ class FlaskGroup(AppGroup): # Push an app context for the loaded app unless it is already # active somehow. This makes the context available to parameter # and command callbacks without needing @with_appcontext. - if not current_app or current_app._get_current_object() is not app: # type: ignore[attr-defined] + if not current_app or current_app._get_current_object() is not app: ctx.with_resource(app.app_context()) return app.cli.get_command(ctx, name) diff --git a/src/flask/ctx.py b/src/flask/ctx.py index 222e818e..1ac86eaf 100644 --- a/src/flask/ctx.py +++ b/src/flask/ctx.py @@ -1,20 +1,20 @@ from __future__ import annotations import contextvars -import sys import typing as t from functools import update_wrapper from types import TracebackType from werkzeug.exceptions import HTTPException +from werkzeug.routing import MapAdapter from . import typing as ft from .globals import _cv_app -from .globals import _cv_request from .signals import appcontext_popped from .signals import appcontext_pushed -if t.TYPE_CHECKING: # pragma: no cover +if t.TYPE_CHECKING: + import typing_extensions as te from _typeshed.wsgi import WSGIEnvironment from .app import Flask @@ -31,7 +31,7 @@ class _AppCtxGlobals: application context. Creating an app context automatically creates this object, which is - made available as the :data:`g` proxy. + made available as the :data:`.g` proxy. .. describe:: 'key' in g @@ -117,29 +117,27 @@ class _AppCtxGlobals: def after_this_request( f: ft.AfterRequestCallable[t.Any], ) -> ft.AfterRequestCallable[t.Any]: - """Executes a function after this request. This is useful to modify - response objects. The function is passed the response object and has - to return the same or a new one. + """Decorate a function to run after the current request. The behavior is the + same as :meth:`.Flask.after_request`, except it only applies to the current + request, rather than every request. Therefore, it must be used within a + request context, rather than during setup. - Example:: + .. code-block:: python - @app.route('/') + @app.route("/") def index(): @after_this_request def add_header(response): - response.headers['X-Foo'] = 'Parachute' + response.headers["X-Foo"] = "Parachute" return response - return 'Hello World!' - This is more useful if a function other than the view function wants to - modify a response. For instance think of a decorator that wants to add - some headers without converting the return value into a response object. + return "Hello, World!" .. versionadded:: 0.9 """ - ctx = _cv_request.get(None) + ctx = _cv_app.get(None) - if ctx is None: + if ctx is None or not ctx.has_request: raise RuntimeError( "'after_this_request' can only be used when a request" " context is active, such as in a view function." @@ -153,13 +151,27 @@ F = t.TypeVar("F", bound=t.Callable[..., t.Any]) def copy_current_request_context(f: F) -> F: - """A helper function that decorates a function to retain the current - request context. This is useful when working with greenlets. The moment - the function is decorated a copy of the request context is created and - then pushed when the function is called. The current session is also - included in the copied request context. + """Decorate a function to run inside the current request context. This can + be used when starting a background task, otherwise it will not see the app + and request objects that were active in the parent. - Example:: + .. warning:: + + Due to the following caveats, it is often safer (and simpler) to pass + the data you need when starting the task, rather than using this and + relying on the context objects. + + In order to avoid execution switching partially though reading data, either + read the request body (access ``form``, ``json``, ``data``, etc) before + starting the task, or use a lock. This can be an issue when using threading, + but shouldn't be an issue when using greenlet/gevent or asyncio. + + If the task will access ``session``, be sure to do so in the parent as well + so that the ``Vary: cookie`` header will be set. Modifying ``session`` in + the task should be avoided, as it may execute after the response cookie has + already been written. + + .. code-block:: python import gevent from flask import copy_current_request_context @@ -176,7 +188,7 @@ def copy_current_request_context(f: F) -> F: .. versionadded:: 0.10 """ - ctx = _cv_request.get(None) + ctx = _cv_app.get(None) if ctx is None: raise RuntimeError( @@ -194,41 +206,50 @@ def copy_current_request_context(f: F) -> F: def has_request_context() -> bool: - """If you have code that wants to test if a request context is there or - not this function can be used. For instance, you may want to take advantage - of request information if the request object is available, but fail - silently if it is unavailable. + """Test if an app context is active and if it has request information. - :: + .. code-block:: python - class User(db.Model): + from flask import has_request_context, request - def __init__(self, username, remote_addr=None): - self.username = username - if remote_addr is None and has_request_context(): - remote_addr = request.remote_addr - self.remote_addr = remote_addr + if has_request_context(): + remote_addr = request.remote_addr - Alternatively you can also just test any of the context bound objects - (such as :class:`request` or :class:`g`) for truthness:: + If a request context is active, the :data:`.request` and :data:`.session` + context proxies will available and ``True``, otherwise ``False``. You can + use that to test the data you use, rather than using this function. - class User(db.Model): + .. code-block:: python - def __init__(self, username, remote_addr=None): - self.username = username - if remote_addr is None and request: - remote_addr = request.remote_addr - self.remote_addr = remote_addr + from flask import request + + if request: + remote_addr = request.remote_addr .. versionadded:: 0.7 """ - return _cv_request.get(None) is not None + return (ctx := _cv_app.get(None)) is not None and ctx.has_request def has_app_context() -> bool: - """Works like :func:`has_request_context` but for the application - context. You can also just do a boolean check on the - :data:`current_app` object instead. + """Test if an app context is active. Unlike :func:`has_request_context` + this can be true outside a request, such as in a CLI command. + + .. code-block:: python + + from flask import has_app_context, g + + if has_app_context(): + g.cached_data = ... + + If an app context is active, the :data:`.g` and :data:`.current_app` context + proxies will available and ``True``, otherwise ``False``. You can use that + to test the data you use, rather than using this function. + + from flask import g + + if g: + g.cached_data = ... .. versionadded:: 0.9 """ @@ -236,214 +257,260 @@ def has_app_context() -> bool: class AppContext: - """The app context contains application-specific information. An app - context is created and pushed at the beginning of each request if - one is not already active. An app context is also pushed when - running CLI commands. - """ + """An app context contains information about an app, and about the request + when handling a request. A context is pushed at the beginning of each + request and CLI command, and popped at the end. The context is referred to + as a "request context" if it has request information, and an "app context" + if not. - def __init__(self, app: Flask) -> None: - self.app = app - self.url_adapter = app.create_url_adapter(None) - self.g: _AppCtxGlobals = app.app_ctx_globals_class() - self._cv_tokens: list[contextvars.Token[AppContext]] = [] + Do not use this class directly. Use :meth:`.Flask.app_context` to create an + app context if needed during setup, and :meth:`.Flask.test_request_context` + to create a request context if needed during tests. - def push(self) -> None: - """Binds the app context to the current context.""" - self._cv_tokens.append(_cv_app.set(self)) - appcontext_pushed.send(self.app, _async_wrapper=self.app.ensure_sync) + When the context is popped, it will evaluate all the teardown functions + registered with :meth:`~flask.Flask.teardown_request` (if handling a + request) then :meth:`.Flask.teardown_appcontext`. - def pop(self, exc: BaseException | None = _sentinel) -> None: # type: ignore - """Pops the app context.""" - try: - if len(self._cv_tokens) == 1: - if exc is _sentinel: - exc = sys.exc_info()[1] - self.app.do_teardown_appcontext(exc) - finally: - ctx = _cv_app.get() - _cv_app.reset(self._cv_tokens.pop()) + When using the interactive debugger, the context will be restored so + ``request`` is still accessible. Similarly, the test client can preserve the + context after the request ends. However, teardown functions may already have + closed some resources such as database connections, and will run again when + the restored context is popped. - if ctx is not self: - raise AssertionError( - f"Popped wrong app context. ({ctx!r} instead of {self!r})" - ) + :param app: The application this context represents. + :param request: The request data this context represents. + :param session: The session data this context represents. If not given, + loaded from the request on first access. - appcontext_popped.send(self.app, _async_wrapper=self.app.ensure_sync) + .. versionchanged:: 3.2 + Merged with ``RequestContext``. The ``RequestContext`` alias will be + removed in Flask 4.0. - def __enter__(self) -> AppContext: - self.push() - return self + .. versionchanged:: 3.2 + A combined app and request context is pushed for every request and CLI + command, rather than trying to detect if an app context is already + pushed. - def __exit__( - self, - exc_type: type | None, - exc_value: BaseException | None, - tb: TracebackType | None, - ) -> None: - self.pop(exc_value) - - -class RequestContext: - """The request context contains per-request information. The Flask - app creates and pushes it at the beginning of the request, then pops - it at the end of the request. It will create the URL adapter and - request object for the WSGI environment provided. - - Do not attempt to use this class directly, instead use - :meth:`~flask.Flask.test_request_context` and - :meth:`~flask.Flask.request_context` to create this object. - - When the request context is popped, it will evaluate all the - functions registered on the application for teardown execution - (:meth:`~flask.Flask.teardown_request`). - - The request context is automatically popped at the end of the - request. When using the interactive debugger, the context will be - restored so ``request`` is still accessible. Similarly, the test - client can preserve the context after the request ends. However, - teardown functions may already have closed some resources such as - database connections. + .. versionchanged:: 3.2 + The session is loaded the first time it is accessed, rather than when + the context is pushed. """ def __init__( self, app: Flask, - environ: WSGIEnvironment, + *, request: Request | None = None, session: SessionMixin | None = None, ) -> None: self.app = app - if request is None: - request = app.request_class(environ) - request.json_module = app.json - self.request: Request = request - self.url_adapter = None - try: - self.url_adapter = app.create_url_adapter(self.request) - except HTTPException as e: - self.request.routing_exception = e - self.flashes: list[tuple[str, str]] | None = None - self.session: SessionMixin | None = session - # Functions that should be executed after the request on the response - # object. These will be called before the regular "after_request" - # functions. + """The application represented by this context. Accessed through + :data:`.current_app`. + """ + + self.g: _AppCtxGlobals = app.app_ctx_globals_class() + """The global data for this context. Accessed through :data:`.g`.""" + + self.url_adapter: MapAdapter | None = None + """The URL adapter bound to the request, or the app if not in a request. + May be ``None`` if binding failed. + """ + + self._request: Request | None = request + self._session: SessionMixin | None = session + self._flashes: list[tuple[str, str]] | None = None self._after_request_functions: list[ft.AfterRequestCallable[t.Any]] = [] - self._cv_tokens: list[ - tuple[contextvars.Token[RequestContext], AppContext | None] - ] = [] + try: + self.url_adapter = app.create_url_adapter(self._request) + except HTTPException as e: + if self._request is not None: + self._request.routing_exception = e - def copy(self) -> RequestContext: - """Creates a copy of this request context with the same request object. - This can be used to move a request context to a different greenlet. - Because the actual request object is the same this cannot be used to - move a request context to a different thread unless access to the - request object is locked. + self._cv_token: contextvars.Token[AppContext] | None = None + """The previous state to restore when popping.""" - .. versionadded:: 0.10 + self._push_count: int = 0 + """Track nested pushes of this context. Cleanup will only run once the + original push has been popped. + """ + + @classmethod + def from_environ(cls, app: Flask, environ: WSGIEnvironment, /) -> te.Self: + """Create an app context with request data from the given WSGI environ. + + :param app: The application this context represents. + :param environ: The request data this context represents. + """ + request = app.request_class(environ) + request.json_module = app.json + return cls(app, request=request) + + @property + def has_request(self) -> bool: + """True if this context was created with request data.""" + return self._request is not None + + def copy(self) -> te.Self: + """Create a new context with the same data objects as this context. See + :func:`.copy_current_request_context`. .. versionchanged:: 1.1 - The current session object is used instead of reloading the original - data. This prevents `flask.session` pointing to an out-of-date object. + The current session data is used instead of reloading the original data. + + .. versionadded:: 0.10 """ return self.__class__( self.app, - environ=self.request.environ, - request=self.request, - session=self.session, + request=self._request, + session=self._session, ) + @property + def request(self) -> Request: + """The request object associated with this context. Accessed through + :data:`.request`. Only available in request contexts, otherwise raises + :exc:`RuntimeError`. + """ + if self._request is None: + raise RuntimeError("There is no request in this context.") + + return self._request + + @property + def session(self) -> SessionMixin: + """The session object associated with this context. Accessed through + :data:`.session`. Only available in request contexts, otherwise raises + :exc:`RuntimeError`. + """ + if self._request is None: + raise RuntimeError("There is no request in this context.") + + if self._session is None: + si = self.app.session_interface + self._session = si.open_session(self.app, self.request) + + if self._session is None: + self._session = si.make_null_session(self.app) + + return self._session + def match_request(self) -> None: - """Can be overridden by a subclass to hook into the matching - of the request. + """Apply routing to the current request, storing either the matched + endpoint and args, or a routing exception. """ try: - result = self.url_adapter.match(return_rule=True) # type: ignore - self.request.url_rule, self.request.view_args = result # type: ignore + result = self.url_adapter.match(return_rule=True) # type: ignore[union-attr] except HTTPException as e: - self.request.routing_exception = e + self._request.routing_exception = e # type: ignore[union-attr] + else: + self._request.url_rule, self._request.view_args = result # type: ignore[union-attr] def push(self) -> None: - # Before we push the request context we have to ensure that there - # is an application context. - app_ctx = _cv_app.get(None) + """Push this context so that it is the active context. If this is a + request context, calls :meth:`match_request` to perform routing with + the context active. - if app_ctx is None or app_ctx.app is not self.app: - app_ctx = self.app.app_context() - app_ctx.push() - else: - app_ctx = None + Typically, this is not used directly. Instead, use a ``with`` block + to manage the context. - self._cv_tokens.append((_cv_request.set(self), app_ctx)) + In some situations, such as streaming or testing, the context may be + pushed multiple times. It will only trigger matching and signals if it + is not currently pushed. + """ + self._push_count += 1 - # Open the session at the moment that the request context is available. - # This allows a custom open_session method to use the request context. - # Only open a new session if this is the first time the request was - # pushed, otherwise stream_with_context loses the session. - if self.session is None: - session_interface = self.app.session_interface - self.session = session_interface.open_session(self.app, self.request) + if self._cv_token is not None: + return - if self.session is None: - self.session = session_interface.make_null_session(self.app) + self._cv_token = _cv_app.set(self) + appcontext_pushed.send(self.app, _async_wrapper=self.app.ensure_sync) - # Match the request URL after loading the session, so that the - # session is available in custom URL converters. - if self.url_adapter is not None: + if self._request is not None and self.url_adapter is not None: self.match_request() - def pop(self, exc: BaseException | None = _sentinel) -> None: # type: ignore - """Pops the request context and unbinds it by doing that. This will - also trigger the execution of functions registered by the - :meth:`~flask.Flask.teardown_request` decorator. + def pop(self, exc: BaseException | None = None) -> None: + """Pop this context so that it is no longer the active context. Then + call teardown functions and signals. + + Typically, this is not used directly. Instead, use a ``with`` block + to manage the context. + + This context must currently be the active context, otherwise a + :exc:`RuntimeError` is raised. In some situations, such as streaming or + testing, the context may have been pushed multiple times. It will only + trigger cleanup once it has been popped as many times as it was pushed. + Until then, it will remain the active context. + + :param exc: An unhandled exception that was raised while the context was + active. Passed to teardown functions. .. versionchanged:: 0.9 - Added the `exc` argument. + Added the ``exc`` argument. """ - clear_request = len(self._cv_tokens) == 1 + if self._cv_token is None: + raise RuntimeError(f"Cannot pop this context ({self!r}), it is not pushed.") + + ctx = _cv_app.get(None) + + if ctx is None or self._cv_token is None: + raise RuntimeError( + f"Cannot pop this context ({self!r}), there is no active context." + ) + + if ctx is not self: + raise RuntimeError( + f"Cannot pop this context ({self!r}), it is not the active" + f" context ({ctx!r})." + ) + + self._push_count -= 1 + + if self._push_count > 0: + return try: - if clear_request: - if exc is _sentinel: - exc = sys.exc_info()[1] + if self._request is not None: self.app.do_teardown_request(exc) - - request_close = getattr(self.request, "close", None) - if request_close is not None: - request_close() + self._request.close() finally: - ctx = _cv_request.get() - token, app_ctx = self._cv_tokens.pop() - _cv_request.reset(token) + self.app.do_teardown_appcontext(exc) + _cv_app.reset(self._cv_token) + self._cv_token = None + appcontext_popped.send(self.app, _async_wrapper=self.app.ensure_sync) - # get rid of circular dependencies at the end of the request - # so that we don't require the GC to be active. - if clear_request: - ctx.request.environ["werkzeug.request"] = None - - if app_ctx is not None: - app_ctx.pop(exc) - - if ctx is not self: - raise AssertionError( - f"Popped wrong request context. ({ctx!r} instead of {self!r})" - ) - - def __enter__(self) -> RequestContext: + def __enter__(self) -> te.Self: self.push() return self def __exit__( self, - exc_type: type | None, + exc_type: type[BaseException] | None, exc_value: BaseException | None, tb: TracebackType | None, ) -> None: self.pop(exc_value) def __repr__(self) -> str: - return ( - f"<{type(self).__name__} {self.request.url!r}" - f" [{self.request.method}] of {self.app.name}>" + if self._request is not None: + return ( + f"<{type(self).__name__} {id(self)} of {self.app.name}," + f" {self.request.method} {self.request.url!r}>" + ) + + return f"<{type(self).__name__} {id(self)} of {self.app.name}>" + + +def __getattr__(name: str) -> t.Any: + import warnings + + if name == "RequestContext": + warnings.warn( + "'RequestContext' has merged with 'AppContext', and will be removed" + " in Flask 4.0. Use 'AppContext' instead.", + DeprecationWarning, + stacklevel=2, ) + return AppContext + + raise AttributeError(name) diff --git a/src/flask/debughelpers.py b/src/flask/debughelpers.py index 2c8c4c48..61884e1a 100644 --- a/src/flask/debughelpers.py +++ b/src/flask/debughelpers.py @@ -6,7 +6,7 @@ from jinja2.loaders import BaseLoader from werkzeug.routing import RequestRedirect from .blueprints import Blueprint -from .globals import request_ctx +from .globals import _cv_app from .sansio.app import App if t.TYPE_CHECKING: @@ -136,8 +136,9 @@ def explain_template_loading_attempts( info = [f"Locating template {template!r}:"] total_found = 0 blueprint = None - if request_ctx and request_ctx.request.blueprint is not None: - blueprint = request_ctx.request.blueprint + + if (ctx := _cv_app.get(None)) is not None and ctx.has_request: + blueprint = ctx.request.blueprint for idx, (loader, srcobj, triple) in enumerate(attempts): if isinstance(srcobj, App): diff --git a/src/flask/globals.py b/src/flask/globals.py index e2c410cc..f4a7298e 100644 --- a/src/flask/globals.py +++ b/src/flask/globals.py @@ -9,43 +9,69 @@ if t.TYPE_CHECKING: # pragma: no cover from .app import Flask from .ctx import _AppCtxGlobals from .ctx import AppContext - from .ctx import RequestContext from .sessions import SessionMixin from .wrappers import Request + T = t.TypeVar("T", covariant=True) + + class ProxyMixin(t.Protocol[T]): + def _get_current_object(self) -> T: ... + + # These subclasses inform type checkers that the proxy objects look like the + # proxied type along with the _get_current_object method. + class FlaskProxy(ProxyMixin[Flask], Flask): ... + + class AppContextProxy(ProxyMixin[AppContext], AppContext): ... + + class _AppCtxGlobalsProxy(ProxyMixin[_AppCtxGlobals], _AppCtxGlobals): ... + + class RequestProxy(ProxyMixin[Request], Request): ... + + class SessionMixinProxy(ProxyMixin[SessionMixin], SessionMixin): ... + _no_app_msg = """\ Working outside of application context. -This typically means that you attempted to use functionality that needed -the current application. To solve this, set up an application context -with app.app_context(). See the documentation for more information.\ +Attempted to use functionality that expected a current application to be set. To +solve this, set up an app context using 'with app.app_context()'. See the +documentation on app context for more information.\ """ _cv_app: ContextVar[AppContext] = ContextVar("flask.app_ctx") -app_ctx: AppContext = LocalProxy( # type: ignore[assignment] +app_ctx: AppContextProxy = LocalProxy( # type: ignore[assignment] _cv_app, unbound_message=_no_app_msg ) -current_app: Flask = LocalProxy( # type: ignore[assignment] +current_app: FlaskProxy = LocalProxy( # type: ignore[assignment] _cv_app, "app", unbound_message=_no_app_msg ) -g: _AppCtxGlobals = LocalProxy( # type: ignore[assignment] +g: _AppCtxGlobalsProxy = LocalProxy( # type: ignore[assignment] _cv_app, "g", unbound_message=_no_app_msg ) _no_req_msg = """\ Working outside of request context. -This typically means that you attempted to use functionality that needed -an active HTTP request. Consult the documentation on testing for -information about how to avoid this problem.\ +Attempted to use functionality that expected an active HTTP request. See the +documentation on request context for more information.\ """ -_cv_request: ContextVar[RequestContext] = ContextVar("flask.request_ctx") -request_ctx: RequestContext = LocalProxy( # type: ignore[assignment] - _cv_request, unbound_message=_no_req_msg +request: RequestProxy = LocalProxy( # type: ignore[assignment] + _cv_app, "request", unbound_message=_no_req_msg ) -request: Request = LocalProxy( # type: ignore[assignment] - _cv_request, "request", unbound_message=_no_req_msg -) -session: SessionMixin = LocalProxy( # type: ignore[assignment] - _cv_request, "session", unbound_message=_no_req_msg +session: SessionMixinProxy = LocalProxy( # type: ignore[assignment] + _cv_app, "session", unbound_message=_no_req_msg ) + + +def __getattr__(name: str) -> t.Any: + import warnings + + if name == "request_ctx": + warnings.warn( + "'request_ctx' has merged with 'app_ctx', and will be removed" + " in Flask 4.0. Use 'app_ctx' instead.", + DeprecationWarning, + stacklevel=2, + ) + return app_ctx + + raise AttributeError(name) diff --git a/src/flask/helpers.py b/src/flask/helpers.py index 5d412c90..31167c2b 100644 --- a/src/flask/helpers.py +++ b/src/flask/helpers.py @@ -14,10 +14,9 @@ from werkzeug.utils import redirect as _wz_redirect from werkzeug.wrappers import Response as BaseResponse from .globals import _cv_app -from .globals import _cv_request +from .globals import app_ctx from .globals import current_app from .globals import request -from .globals import request_ctx from .globals import session from .signals import message_flashed @@ -64,7 +63,7 @@ def stream_with_context( generator_or_function: t.Iterator[t.AnyStr] | t.Callable[..., t.Iterator[t.AnyStr]], ) -> t.Iterator[t.AnyStr] | t.Callable[[t.Iterator[t.AnyStr]], t.Iterator[t.AnyStr]]: """Wrap a response generator function so that it runs inside the current - request context. This keeps :data:`request`, :data:`session`, and :data:`g` + request context. This keeps :data:`.request`, :data:`.session`, and :data:`.g` available, even though at the point the generator runs the request context will typically have ended. @@ -112,22 +111,15 @@ def stream_with_context( return update_wrapper(decorator, generator_or_function) # type: ignore[arg-type] def generator() -> t.Iterator[t.AnyStr]: - if (req_ctx := _cv_request.get(None)) is None: + if (ctx := _cv_app.get(None)) is None: raise RuntimeError( "'stream_with_context' can only be used when a request" " context is active, such as in a view function." ) - app_ctx = _cv_app.get() - # Setup code below will run the generator to this point, so that the - # current contexts are recorded. The contexts must be pushed after, - # otherwise their ContextVar will record the wrong event loop during - # async view functions. - yield None # type: ignore[misc] + with ctx: + yield None # type: ignore[misc] - # Push the app context first, so that the request context does not - # automatically create and push a different app context. - with app_ctx, req_ctx: try: yield from gen finally: @@ -135,9 +127,9 @@ def stream_with_context( if hasattr(gen, "close"): gen.close() - # Execute the generator to the sentinel value. This ensures the context is - # preserved in the generator's state. Further iteration will push the - # context and yield from the original iterator. + # Execute the generator to the sentinel value. This captures the current + # context and pushes it to preserve it. Further iteration will yield from + # the original iterator. wrapped_g = generator() next(wrapped_g) return wrapped_g @@ -264,8 +256,8 @@ def redirect( Calls ``current_app.redirect`` if available instead of always using Werkzeug's default ``redirect``. """ - if current_app: - return current_app.redirect(location, code=code) + if (ctx := _cv_app.get(None)) is not None: + return ctx.app.redirect(location, code=code) return _wz_redirect(location, code=code, Response=Response) @@ -287,8 +279,8 @@ def abort(code: int | BaseResponse, *args: t.Any, **kwargs: t.Any) -> t.NoReturn Calls ``current_app.aborter`` if available instead of always using Werkzeug's default ``abort``. """ - if current_app: - current_app.aborter(code, *args, **kwargs) + if (ctx := _cv_app.get(None)) is not None: + ctx.app.aborter(code, *args, **kwargs) _wz_abort(code, *args, **kwargs) @@ -340,7 +332,7 @@ def flash(message: str, category: str = "message") -> None: flashes = session.get("_flashes", []) flashes.append((category, message)) session["_flashes"] = flashes - app = current_app._get_current_object() # type: ignore + app = current_app._get_current_object() message_flashed.send( app, _async_wrapper=app.ensure_sync, @@ -380,10 +372,10 @@ def get_flashed_messages( :param category_filter: filter of categories to limit return values. Only categories in the list will be returned. """ - flashes = request_ctx.flashes + flashes = app_ctx._flashes if flashes is None: flashes = session.pop("_flashes") if "_flashes" in session else [] - request_ctx.flashes = flashes + app_ctx._flashes = flashes if category_filter: flashes = list(filter(lambda f: f[0] in category_filter, flashes)) if not with_categories: @@ -392,14 +384,16 @@ def get_flashed_messages( def _prepare_send_file_kwargs(**kwargs: t.Any) -> dict[str, t.Any]: + ctx = app_ctx._get_current_object() + if kwargs.get("max_age") is None: - kwargs["max_age"] = current_app.get_send_file_max_age + kwargs["max_age"] = ctx.app.get_send_file_max_age kwargs.update( - environ=request.environ, - use_x_sendfile=current_app.config["USE_X_SENDFILE"], - response_class=current_app.response_class, - _root_path=current_app.root_path, + environ=ctx.request.environ, + use_x_sendfile=ctx.app.config["USE_X_SENDFILE"], + response_class=ctx.app.response_class, + _root_path=ctx.app.root_path, ) return kwargs diff --git a/src/flask/json/__init__.py b/src/flask/json/__init__.py index c0941d04..742812f2 100644 --- a/src/flask/json/__init__.py +++ b/src/flask/json/__init__.py @@ -141,7 +141,7 @@ def jsonify(*args: t.Any, **kwargs: t.Any) -> Response: mimetype. A dict or list returned from a view will be converted to a JSON response automatically without needing to call this. - This requires an active request or application context, and calls + This requires an active app context, and calls :meth:`app.json.response() `. In debug mode, the output is formatted with indentation to make it diff --git a/src/flask/sansio/app.py b/src/flask/sansio/app.py index 94bd43a5..43d20529 100644 --- a/src/flask/sansio/app.py +++ b/src/flask/sansio/app.py @@ -177,11 +177,8 @@ class App(Scaffold): #: 3. Return None instead of AttributeError on unexpected attributes. #: 4. Raise exception if an unexpected attr is set, a "controlled" flask.g. #: - #: In Flask 0.9 this property was called `request_globals_class` but it - #: was changed in 0.10 to :attr:`app_ctx_globals_class` because the - #: flask.g object is now application context scoped. - #: #: .. versionadded:: 0.10 + #: Renamed from ``request_globals_class`. app_ctx_globals_class = _AppCtxGlobals #: The class that is used for the ``config`` attribute of this app. @@ -825,10 +822,9 @@ class App(Scaffold): @setupmethod def teardown_appcontext(self, f: T_teardown) -> T_teardown: - """Registers a function to be called when the application - context is popped. The application context is typically popped - after the request context for each request, at the end of CLI - commands, or after a manually pushed context ends. + """Registers a function to be called when the app context is popped. The + context is popped at the end of a request, CLI command, or manual ``with`` + block. .. code-block:: python @@ -837,9 +833,7 @@ class App(Scaffold): When the ``with`` block exits (or ``ctx.pop()`` is called), the teardown functions are called just before the app context is - made inactive. Since a request context typically also manages an - application context it would also be called when you pop a - request context. + made inactive. When a teardown function was called because of an unhandled exception it will be passed an error object. If an diff --git a/src/flask/sansio/scaffold.py b/src/flask/sansio/scaffold.py index 0e96f15b..a04c38ad 100644 --- a/src/flask/sansio/scaffold.py +++ b/src/flask/sansio/scaffold.py @@ -507,8 +507,8 @@ class Scaffold: @setupmethod def teardown_request(self, f: T_teardown) -> T_teardown: """Register a function to be called when the request context is - popped. Typically this happens at the end of each request, but - contexts may be pushed manually as well during testing. + popped. Typically, this happens at the end of each request, but + contexts may be pushed manually during testing. .. code-block:: python diff --git a/src/flask/templating.py b/src/flask/templating.py index 16d480f5..9a0ace84 100644 --- a/src/flask/templating.py +++ b/src/flask/templating.py @@ -8,9 +8,7 @@ from jinja2 import Template from jinja2 import TemplateNotFound from .globals import _cv_app -from .globals import _cv_request from .globals import current_app -from .globals import request from .helpers import stream_with_context from .signals import before_render_template from .signals import template_rendered @@ -25,14 +23,16 @@ def _default_template_ctx_processor() -> dict[str, t.Any]: """Default template context processor. Injects `request`, `session` and `g`. """ - appctx = _cv_app.get(None) - reqctx = _cv_request.get(None) + ctx = _cv_app.get(None) rv: dict[str, t.Any] = {} - if appctx is not None: - rv["g"] = appctx.g - if reqctx is not None: - rv["request"] = reqctx.request - rv["session"] = reqctx.session + + if ctx is not None: + rv["g"] = ctx.g + + if ctx.has_request: + rv["request"] = ctx.request + rv["session"] = ctx.session + return rv @@ -145,7 +145,7 @@ def render_template( a list is given, the first name to exist will be rendered. :param context: The variables to make available in the template. """ - app = current_app._get_current_object() # type: ignore[attr-defined] + app = current_app._get_current_object() template = app.jinja_env.get_or_select_template(template_name_or_list) return _render(app, template, context) @@ -157,7 +157,7 @@ def render_template_string(source: str, **context: t.Any) -> str: :param source: The source code of the template to render. :param context: The variables to make available in the template. """ - app = current_app._get_current_object() # type: ignore[attr-defined] + app = current_app._get_current_object() template = app.jinja_env.from_string(source) return _render(app, template, context) @@ -176,13 +176,7 @@ def _stream( app, _async_wrapper=app.ensure_sync, template=template, context=context ) - rv = generate() - - # If a request context is active, keep it while generating. - if request: - rv = stream_with_context(rv) - - return rv + return stream_with_context(generate()) def stream_template( @@ -199,7 +193,7 @@ def stream_template( .. versionadded:: 2.2 """ - app = current_app._get_current_object() # type: ignore[attr-defined] + app = current_app._get_current_object() template = app.jinja_env.get_or_select_template(template_name_or_list) return _stream(app, template, context) @@ -214,6 +208,6 @@ def stream_template_string(source: str, **context: t.Any) -> t.Iterator[str]: .. versionadded:: 2.2 """ - app = current_app._get_current_object() # type: ignore[attr-defined] + app = current_app._get_current_object() template = app.jinja_env.from_string(source) return _stream(app, template, context) diff --git a/src/flask/testing.py b/src/flask/testing.py index 55eb12fe..68b1ab48 100644 --- a/src/flask/testing.py +++ b/src/flask/testing.py @@ -107,10 +107,10 @@ def _get_werkzeug_version() -> str: class FlaskClient(Client): - """Works like a regular Werkzeug test client but has knowledge about - Flask's contexts to defer the cleanup of the request context until - the end of a ``with`` block. For general information about how to - use this class refer to :class:`werkzeug.test.Client`. + """Works like a regular Werkzeug test client, with additional behavior for + Flask. Can defer the cleanup of the request context until the end of a + ``with`` block. For general information about how to use this class refer to + :class:`werkzeug.test.Client`. .. versionchanged:: 0.12 `app.test_client()` includes preset default environment, which can be diff --git a/tests/conftest.py b/tests/conftest.py index 214f5203..0414b9e2 100644 --- a/tests/conftest.py +++ b/tests/conftest.py @@ -5,7 +5,7 @@ import pytest from _pytest import monkeypatch from flask import Flask -from flask.globals import request_ctx +from flask.globals import app_ctx as _app_ctx @pytest.fixture(scope="session", autouse=True) @@ -83,16 +83,17 @@ def test_apps(monkeypatch): @pytest.fixture(autouse=True) def leak_detector(): + """Fails if any app contexts are still pushed when a test ends. Pops all + contexts so subsequent tests are not affected. + """ yield - - # make sure we're not leaking a request context since we are - # testing flask internally in debug mode in a few cases leaks = [] - while request_ctx: - leaks.append(request_ctx._get_current_object()) - request_ctx.pop() - assert leaks == [] + while _app_ctx: + leaks.append(_app_ctx._get_current_object()) + _app_ctx.pop() + + assert not leaks @pytest.fixture diff --git a/tests/test_appctx.py b/tests/test_appctx.py index ca9e079e..a537b050 100644 --- a/tests/test_appctx.py +++ b/tests/test_appctx.py @@ -2,7 +2,6 @@ import pytest import flask from flask.globals import app_ctx -from flask.globals import request_ctx def test_basic_url_generation(app): @@ -107,7 +106,8 @@ def test_app_tearing_down_with_handled_exception_by_app_handler(app, client): with app.app_context(): client.get("/") - assert cleanup_stuff == [None] + # teardown request context, and with block context + assert cleanup_stuff == [None, None] def test_app_tearing_down_with_unhandled_exception(app, client): @@ -126,9 +126,11 @@ def test_app_tearing_down_with_unhandled_exception(app, client): with app.app_context(): client.get("/") - assert len(cleanup_stuff) == 1 + assert len(cleanup_stuff) == 2 assert isinstance(cleanup_stuff[0], ValueError) assert str(cleanup_stuff[0]) == "dummy" + # exception propagated, seen by request context and with block context + assert cleanup_stuff[0] is cleanup_stuff[1] def test_app_ctx_globals_methods(app, app_ctx): @@ -178,8 +180,7 @@ def test_context_refcounts(app, client): @app.route("/") def index(): with app_ctx: - with request_ctx: - pass + pass assert flask.request.environ["werkzeug.request"] is not None return "" diff --git a/tests/test_reqctx.py b/tests/test_reqctx.py index 6c38b661..a7b77eb9 100644 --- a/tests/test_reqctx.py +++ b/tests/test_reqctx.py @@ -3,7 +3,7 @@ import warnings import pytest import flask -from flask.globals import request_ctx +from flask.globals import app_ctx from flask.sessions import SecureCookieSessionInterface from flask.sessions import SessionInterface @@ -153,12 +153,12 @@ class TestGreenletContextCopying: @app.route("/") def index(): flask.session["fizz"] = "buzz" - reqctx = request_ctx.copy() + ctx = app_ctx.copy() def g(): assert not flask.request assert not flask.current_app - with reqctx: + with ctx: assert flask.request assert flask.current_app == app assert flask.request.path == "/" diff --git a/tests/test_session_interface.py b/tests/test_session_interface.py index 613da37f..5564be74 100644 --- a/tests/test_session_interface.py +++ b/tests/test_session_interface.py @@ -1,5 +1,5 @@ import flask -from flask.globals import request_ctx +from flask.globals import app_ctx from flask.sessions import SessionInterface @@ -14,7 +14,7 @@ def test_open_session_with_endpoint(): pass def open_session(self, app, request): - request_ctx.match_request() + app_ctx.match_request() assert request.endpoint is not None app = flask.Flask(__name__) diff --git a/tests/test_testing.py b/tests/test_testing.py index 20f9f6dd..e14f27cc 100644 --- a/tests/test_testing.py +++ b/tests/test_testing.py @@ -6,7 +6,7 @@ import pytest import flask from flask import appcontext_popped from flask.cli import ScriptInfo -from flask.globals import _cv_request +from flask.globals import _cv_app from flask.json import jsonify from flask.testing import EnvironBuilder from flask.testing import FlaskCliRunner @@ -382,4 +382,4 @@ def test_client_pop_all_preserved(app, req_ctx, client): # close the response, releasing the context held by stream_with_context rv.close() # only req_ctx fixture should still be pushed - assert _cv_request.get(None) is req_ctx + assert _cv_app.get(None) is req_ctx