mirror of https://github.com/pallets/flask.git
Merge branch 'blueprints' of github.com:mitsuhiko/flask into blueprints
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5ca333e9b7
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@ -5,42 +5,51 @@ Modular Applications with Blueprints
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.. versionadded:: 0.7
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Flask knows a concept known as “blueprints” which can greatly simplify how
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large applications work. A blueprint is an object works similar to an
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actual :class:`Flask` application object, but it is not actually an
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application. Rather it is the blueprint of how to create an application.
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Think of it like that: you might want to have an application that has a
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wiki. So what you can do is creating the blueprint for a wiki and then
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let the application assemble the wiki on the application object.
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Flask uses a concept of *blueprints* for making application components and
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supporting common patterns within an application or across applications.
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Blueprints can greatly simplify how large applications work and provide a
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central means for Flask extensions to register operations on applications.
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A :class:`Blueprint` object works similarly to a :class:`Flask`
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application object, but it is not actually an application. Rather it is a
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*blueprint* of how to construct or extend an application.
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Why Blueprints?
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---------------
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Why have blueprints and not multiple application objects? The utopia of
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pluggable applications are different WSGI applications and merging them
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together somehow. You can do that (see :ref:`app-dispatch`) but it's not
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the right tool for every case. Having different applications means having
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different configs. Applications are also separated on the WSGI layer
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which is a lot lower level than the level that Flask usually operates on
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where you have request and response objects.
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Blueprints in Flask are intended for these cases:
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Blueprints do not necessarily have to implement applications. They could
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only provide filters for templates, static files, templates or similar
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things. They share the same config as the application and can change the
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application as necessary when being registered.
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* Factor an application into a set of blueprints. This is ideal for
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larger applications; a project could instantiate an application object,
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initialize several extensions, and register a collection of blueprints.
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* Register a blueprint on an application at a URL prefix and/or subdomain.
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Paremeters in the URL prefix/subdomain become common view arguments
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(with defaults) across all view functions in the blueprint.
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* Register a blueprint multiple times on an application with different URL
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rules.
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* Provide template filters, static files, templates, and other utilities
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through blueprints. A blueprint does not have to implement applications
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or view functions.
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* Register a blueprint on an application for any of these cases when
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initializing a Flask extension.
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The downside is that you cannot unregister a blueprint once application
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without having to destroy the whole application object.
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A blueprint in Flask is not a pluggable app because it is not actually an
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application -- it's a set of operations which can be registered on an
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application, even multiple times. Why not have multiple application
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objects? You can do that (see :ref:`app-dispatch`), but your applications
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will have separate configs and will be managed at the WSGI layer.
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Blueprints instead provide separation at the Flask level, share
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application config, and can change an application object as necessary with
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being registered. The downside is that you cannot unregister a blueprint
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once application without having to destroy the whole application object.
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The Concept of Blueprints
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-------------------------
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The basic concept of blueprints is that they record operations that should
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be executed when the blueprint is registered on the application. However
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additionally each time a request gets dispatched to a view that was
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declared to a blueprint Flask will remember that the request was
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dispatched to that blueprint. That way it's easier to generate URLs from
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one endpoint to another in the same module.
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The basic concept of blueprints is that they record operations to execute
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when registered on an application. Flask associates view functions with
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blueprints when dispatching requests and generating URLs from one endpoint
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to another.
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My First Blueprint
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------------------
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@ -174,13 +174,14 @@ It's easy to see the behavior from the command line:
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>>> app = Flask(__name__)
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>>> @app.teardown_request
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... def after_request(exception=None):
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... print 'after request'
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...
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... def teardown_request(exception=None):
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... print 'this runs after request'
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...
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>>> ctx = app.test_request_context()
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>>> ctx.push()
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>>> ctx.pop()
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after request
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this runs after request
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>>>
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.. _notes-on-proxies:
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@ -124,8 +124,8 @@ class Blueprint(_PackageBoundObject):
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deferred(state)
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def route(self, rule, **options):
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"""Like :meth:`Flask.route` but for a module. The endpoint for the
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:func:`url_for` function is prefixed with the name of the module.
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"""Like :meth:`Flask.route` but for a blueprint. The endpoint for the
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:func:`url_for` function is prefixed with the name of the blueprint.
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"""
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def decorator(f):
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self.add_url_rule(rule, f.__name__, f, **options)
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@ -133,15 +133,15 @@ class Blueprint(_PackageBoundObject):
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return decorator
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def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
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"""Like :meth:`Flask.add_url_rule` but for a module. The endpoint for
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the :func:`url_for` function is prefixed with the name of the module.
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"""Like :meth:`Flask.add_url_rule` but for a blueprint. The endpoint for
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the :func:`url_for` function is prefixed with the name of the blueprint.
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"""
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self.record(lambda s:
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s.add_url_rule(rule, endpoint, view_func, **options))
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def endpoint(self, endpoint):
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"""Like :meth:`Flask.endpoint` but for a module. This does not
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prefix the endpoint with the module name, this has to be done
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"""Like :meth:`Flask.endpoint` but for a blueprint. This does not
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prefix the endpoint with the blueprint name, this has to be done
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explicitly by the user of this method. If the endpoint is prefixed
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with a `.` it will be registered to the current blueprint, otherwise
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it's an application independent endpoint.
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@ -154,9 +154,9 @@ class Blueprint(_PackageBoundObject):
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return decorator
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def before_request(self, f):
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"""Like :meth:`Flask.before_request` but for a module. This function
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"""Like :meth:`Flask.before_request` but for a blueprint. This function
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is only executed before each request that is handled by a function of
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that module.
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that blueprint.
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"""
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self.record_once(lambda s: s.app.before_request_funcs
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.setdefault(self.name, []).append(f))
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@ -164,48 +164,48 @@ class Blueprint(_PackageBoundObject):
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def before_app_request(self, f):
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"""Like :meth:`Flask.before_request`. Such a function is executed
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before each request, even if outside of a module.
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before each request, even if outside of a blueprint.
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"""
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self.record_once(lambda s: s.app.before_request_funcs
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.setdefault(None, []).append(f))
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return f
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def after_request(self, f):
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"""Like :meth:`Flask.after_request` but for a module. This function
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"""Like :meth:`Flask.after_request` but for a blueprint. This function
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is only executed after each request that is handled by a function of
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that module.
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that blueprint.
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"""
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self.record_once(lambda s: s.app.after_request_funcs
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.setdefault(self.name, []).append(f))
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return f
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def after_app_request(self, f):
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"""Like :meth:`Flask.after_request` but for a module. Such a function
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is executed after each request, even if outside of the module.
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"""Like :meth:`Flask.after_request` but for a blueprint. Such a function
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is executed after each request, even if outside of the blueprint.
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"""
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self.record_once(lambda s: s.app.after_request_funcs
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.setdefault(None, []).append(f))
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return f
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def context_processor(self, f):
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"""Like :meth:`Flask.context_processor` but for a module. This
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function is only executed for requests handled by a module.
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"""Like :meth:`Flask.context_processor` but for a blueprint. This
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function is only executed for requests handled by a blueprint.
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"""
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self.record_once(lambda s: s.app.template_context_processors
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.setdefault(self.name, []).append(f))
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return f
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def app_context_processor(self, f):
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"""Like :meth:`Flask.context_processor` but for a module. Such a
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function is executed each request, even if outside of the module.
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"""Like :meth:`Flask.context_processor` but for a blueprint. Such a
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function is executed each request, even if outside of the blueprint.
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"""
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self.record_once(lambda s: s.app.template_context_processors
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.setdefault(None, []).append(f))
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return f
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def app_errorhandler(self, code):
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"""Like :meth:`Flask.errorhandler` but for a module. This
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handler is used for all requests, even if outside of the module.
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"""Like :meth:`Flask.errorhandler` but for a blueprint. This
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handler is used for all requests, even if outside of the blueprint.
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"""
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def decorator(f):
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self.record_once(lambda s: s.app.errorhandler(code)(f))
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@ -222,7 +222,7 @@ class Blueprint(_PackageBoundObject):
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return f
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def url_defaults(self, f):
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"""Callback function for URL defaults for this module. It's called
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"""Callback function for URL defaults for this blueprint. It's called
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with the endpoint and values and should update the values passed
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in place.
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"""
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