mirror of https://github.com/pallets/flask.git
131 lines
4.8 KiB
Python
131 lines
4.8 KiB
Python
# -*- coding: utf-8 -*-
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"""
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flask.ctx
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~~~~~~~~~
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Implements the objects required to keep the context.
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:copyright: (c) 2010 by Armin Ronacher.
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:license: BSD, see LICENSE for more details.
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"""
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from werkzeug.exceptions import HTTPException
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from .globals import _request_ctx_stack
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from .session import _NullSession
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class _RequestGlobals(object):
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pass
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def has_request_context():
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"""If you have code that wants to test if a request context is there or
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not this function can be used. For instance if you want to take advantage
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of request information is it's available but fail silently if the request
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object is unavailable.
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::
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class User(db.Model):
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def __init__(self, username, remote_addr=None):
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self.username = username
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if remote_addr is None and has_request_context():
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remote_addr = request.remote_addr
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self.remote_addr = remote_addr
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Alternatively you can also just test any of the context bound objects
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(such as :class:`request` or :class:`g` for truthness)::
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class User(db.Model):
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def __init__(self, username, remote_addr=None):
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self.username = username
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if remote_addr is None and request:
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remote_addr = request.remote_addr
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self.remote_addr = remote_addr
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.. versionadded:: 0.7
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"""
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return _request_ctx_stack.top is not None
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class RequestContext(object):
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"""The request context contains all request relevant information. It is
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created at the beginning of the request and pushed to the
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`_request_ctx_stack` and removed at the end of it. It will create the
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URL adapter and request object for the WSGI environment provided.
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Do not attempt to use this class directly, instead use
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:meth:`~flask.Flask.test_request_context` and
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:meth:`~flask.Flask.request_context` to create this object.
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When the request context is popped, it will evaluate all the
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functions registered on the application for teardown execution
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(:meth:`~flask.Flask.teardown_request`).
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The request context is automatically popped at the end of the request
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for you. In debug mode the request context is kept around if
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exceptions happen so that interactive debuggers have a chance to
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introspect the data. With 0.4 this can also be forced for requests
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that did not fail and outside of `DEBUG` mode. By setting
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``'flask._preserve_context'`` to `True` on the WSGI environment the
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context will not pop itself at the end of the request. This is used by
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the :meth:`~flask.Flask.test_client` for example to implement the
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deferred cleanup functionality.
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You might find this helpful for unittests where you need the
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information from the context local around for a little longer. Make
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sure to properly :meth:`~werkzeug.LocalStack.pop` the stack yourself in
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that situation, otherwise your unittests will leak memory.
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"""
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def __init__(self, app, environ):
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self.app = app
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self.request = app.request_class(environ)
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self.url_adapter = app.create_url_adapter(self.request)
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self.g = _RequestGlobals()
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self.flashes = None
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self.session = None
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try:
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url_rule, self.request.view_args = \
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self.url_adapter.match(return_rule=True)
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self.request.url_rule = url_rule
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except HTTPException, e:
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self.request.routing_exception = e
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def push(self):
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"""Binds the request context to the current context."""
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_request_ctx_stack.push(self)
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# Open the session at the moment that the request context is
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# available. This allows a custom open_session method to use the
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# request context (e.g. flask-sqlalchemy).
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self.session = self.app.open_session(self.request)
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if self.session is None:
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self.session = _NullSession()
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def pop(self):
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"""Pops the request context and unbinds it by doing that. This will
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also trigger the execution of functions registered by the
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:meth:`~flask.Flask.teardown_request` decorator.
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"""
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self.app.do_teardown_request()
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_request_ctx_stack.pop()
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def __enter__(self):
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self.push()
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return self
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def __exit__(self, exc_type, exc_value, tb):
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# do not pop the request stack if we are in debug mode and an
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# exception happened. This will allow the debugger to still
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# access the request object in the interactive shell. Furthermore
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# the context can be force kept alive for the test client.
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# See flask.testing for how this works.
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if not self.request.environ.get('flask._preserve_context') and \
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(tb is None or not self.app.preserve_context_on_exception):
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self.pop()
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