Merge remote-tracking branch 'origin/2.0.x' into main

CHANGES.rst

@@ -13,11 +13,14 @@ Version 2.0.2
 
 Unreleased
 
--   Fix type annotation for ``teardown_request``. :issue:`4093`
+-   Fix type annotation for ``teardown_*`` methods. :issue:`4093`
 -   Fix type annotation for ``before_request`` and ``before_app_request``
     decorators. :issue:`4104`
 -   Fixed the issue where typing requires template global
     decorators to accept functions with no arguments. :issue:`4098`
+-   Support View and MethodView instances with async handlers. :issue:`4112`
+-   Enhance typing of ``app.errorhandler`` decorator. :issue:`4095`
+-   Fix registering a blueprint twice with differing names. :issue:`4124`
 
 
 Version 2.0.1

CONTRIBUTING.rst

@@ -12,14 +12,16 @@ to address bugs and feature requests in Flask itself. Use one of the
 following resources for questions about using Flask or issues with your
 own code:
 
--   The ``#get-help`` channel on our Discord chat:
+-   The ``#questions`` channel on our Discord chat:
     https://discord.gg/pallets
 -   The mailing list flask@python.org for long term discussion or larger
     issues.
 -   Ask on `Stack Overflow`_. Search with Google first using:
     ``site:stackoverflow.com flask {search term, exception message, etc.}``
+-   Ask on our `GitHub Discussions`_.
 
 .. _Stack Overflow: https://stackoverflow.com/questions/tagged/flask?tab=Frequent
+.. _GitHub Discussions: https://github.com/pallets/flask/discussions
 
 
 Reporting issues
@@ -92,7 +94,7 @@ First time setup
 
     .. code-block:: text
 
-        git remote add fork https://github.com/{username}/flask
+        $ git remote add fork https://github.com/{username}/flask
 
 -   Create a virtualenv.
 

docs/async-await.rst

@@ -7,7 +7,8 @@ Using ``async`` and ``await``
 
 Routes, error handlers, before request, after request, and teardown
 functions can all be coroutine functions if Flask is installed with the
-``async`` extra (``pip install flask[async]``). This allows views to be
+``async`` extra (``pip install flask[async]``). It requires Python 3.7+
+where ``contextvars.ContextVar`` is available. This allows views to be
 defined with ``async def`` and use ``await``.
 
 .. code-block:: python
@@ -17,6 +18,12 @@ defined with ``async def`` and use ``await``.
         data = await async_db_query(...)
         return jsonify(data)
 
+Pluggable class-based views also support handlers that are implemented as
+coroutines. This applies to the :meth:`~flask.views.View.dispatch_request`
+method in views that inherit from the :class:`flask.views.View` class, as
+well as all the HTTP method handlers in views that inherit from the
+:class:`flask.views.MethodView` class.
+
 .. admonition:: Using ``async`` on Windows on Python 3.8
 
     Python 3.8 has a bug related to asyncio on Windows. If you encounter

docs/installation.rst

@@ -8,6 +8,8 @@ Python Version
 We recommend using the latest version of Python. Flask supports Python
 3.6 and newer.
 
+``async`` support in Flask requires Python 3.7+ for ``contextvars.ContextVar``.
+
 
 Dependencies
 ------------

docs/patterns/celery.rst

@@ -64,7 +64,7 @@ An example task
 
 Let's write a task that adds two numbers together and returns the result. We
 configure Celery's broker and backend to use Redis, create a ``celery``
-application using the factor from above, and then use it to define the task. ::
+application using the factory from above, and then use it to define the task. ::
 
     from flask import Flask
 

docs/quickstart.rst

@@ -444,9 +444,9 @@ Here is an example template:
       <h1>Hello, World!</h1>
     {% endif %}
 
-Inside templates you also have access to the :class:`~flask.request`,
+Inside templates you also have access to the :data:`~flask.Flask.config`,
-:class:`~flask.session` and :class:`~flask.g` [#]_ objects
+:class:`~flask.request`, :class:`~flask.session` and :class:`~flask.g` [#]_ objects
-as well as the :func:`~flask.get_flashed_messages` function.
+as well as the :func:`~flask.url_for` and :func:`~flask.get_flashed_messages` functions.
 
 Templates are especially useful if inheritance is used.  If you want to
 know how that works, see :doc:`patterns/templateinheritance`. Basically

docs/templating.rst

@@ -37,7 +37,7 @@ by default:
 .. data:: config
    :noindex:
 
-   The current configuration object (:data:`flask.config`)
+   The current configuration object (:data:`flask.Flask.config`)
 
    .. versionadded:: 0.6
 

docs/testing.rst

@@ -48,20 +48,21 @@ the application for testing and initializes a new database::
     import pytest
 
     from flaskr import create_app
+    from flaskr.db import init_db
 
 
     @pytest.fixture
     def client():
-        db_fd, flaskr.app.config['DATABASE'] = tempfile.mkstemp()
+        db_fd, db_path = tempfile.mkstemp()
-        flaskr.app.config['TESTING'] = True
+        app = create_app({'TESTING': True, 'DATABASE': db_path})
 
-        with flaskr.app.test_client() as client:
+        with app.test_client() as client:
-            with flaskr.app.app_context():
+            with app.app_context():
-                flaskr.init_db()
+                init_db()
             yield client
 
         os.close(db_fd)
-        os.unlink(flaskr.app.config['DATABASE'])
+        os.unlink(db_path)
 
 This client fixture will be called by each individual test.  It gives us a
 simple interface to the application, where we can trigger test requests to the
@@ -224,13 +225,13 @@ temporarily.  With this you can access the :class:`~flask.request`,
 :class:`~flask.g` and :class:`~flask.session` objects like in view
 functions.  Here is a full example that demonstrates this approach::
 
-    import flask
+    from flask import Flask, request
 
-    app = flask.Flask(__name__)
+    app = Flask(__name__)
 
     with app.test_request_context('/?name=Peter'):
-        assert flask.request.path == '/'
+        assert request.path == '/'
-        assert flask.request.args['name'] == 'Peter'
+        assert request.args['name'] == 'Peter'
 
 All the other objects that are context bound can be used in the same
 way.
@@ -247,7 +248,7 @@ the test request context leaves the ``with`` block.  If you do want the
 :meth:`~flask.Flask.before_request` functions to be called as well, you
 need to call :meth:`~flask.Flask.preprocess_request` yourself::
 
-    app = flask.Flask(__name__)
+    app = Flask(__name__)
 
     with app.test_request_context('/?name=Peter'):
         app.preprocess_request()
@@ -260,7 +261,7 @@ If you want to call the :meth:`~flask.Flask.after_request` functions you
 need to call into :meth:`~flask.Flask.process_response` which however
 requires that you pass it a response object::
 
-    app = flask.Flask(__name__)
+    app = Flask(__name__)
 
     with app.test_request_context('/?name=Peter'):
         resp = Response('...')
@@ -329,7 +330,7 @@ context around for a little longer so that additional introspection can
 happen.  With Flask 0.4 this is possible by using the
 :meth:`~flask.Flask.test_client` with a ``with`` block::
 
-    app = flask.Flask(__name__)
+    app = Flask(__name__)
 
     with app.test_client() as c:
         rv = c.get('/?tequila=42')
@@ -353,7 +354,7 @@ keep the context around and access :data:`flask.session`::
 
     with app.test_client() as c:
         rv = c.get('/')
-        assert flask.session['foo'] == 42
+        assert session['foo'] == 42
 
 This however does not make it possible to also modify the session or to
 access the session before a request was fired.  Starting with Flask 0.8 we

src/flask/app.py

@@ -61,7 +61,6 @@ from .templating import Environment
 from .typing import AfterRequestCallable
 from .typing import BeforeFirstRequestCallable
 from .typing import BeforeRequestCallable
-from .typing import ErrorHandlerCallable
 from .typing import ResponseReturnValue
 from .typing import TeardownCallable
 from .typing import TemplateContextProcessorCallable
@@ -78,6 +77,7 @@ if t.TYPE_CHECKING:
     from .blueprints import Blueprint
     from .testing import FlaskClient
     from .testing import FlaskCliRunner
+    from .typing import ErrorHandlerCallable
 
 if sys.version_info >= (3, 8):
     iscoroutinefunction = inspect.iscoroutinefunction
@@ -1268,7 +1268,9 @@ class Flask(Scaffold):
         self.shell_context_processors.append(f)
         return f
 
-    def _find_error_handler(self, e: Exception) -> t.Optional[ErrorHandlerCallable]:
+    def _find_error_handler(
+        self, e: Exception
+    ) -> t.Optional["ErrorHandlerCallable[Exception]"]:
         """Return a registered error handler for an exception in this order:
         blueprint handler for a specific code, app handler for a specific code,
         blueprint handler for an exception class, app handler for an exception
@@ -1276,7 +1278,7 @@ class Flask(Scaffold):
         """
         exc_class, code = self._get_exc_class_and_code(type(e))
 
-        for c in [code, None]:
+        for c in [code, None] if code is not None else [None]:
             for name in chain(request.blueprints, [None]):
                 handler_map = self.error_handler_spec[name][c]
 

src/flask/blueprints.py

@@ -8,7 +8,6 @@ from .scaffold import Scaffold
 from .typing import AfterRequestCallable
 from .typing import BeforeFirstRequestCallable
 from .typing import BeforeRequestCallable
-from .typing import ErrorHandlerCallable
 from .typing import TeardownCallable
 from .typing import TemplateContextProcessorCallable
 from .typing import TemplateFilterCallable
@@ -19,6 +18,7 @@ from .typing import URLValuePreprocessorCallable
 
 if t.TYPE_CHECKING:
     from .app import Flask
+    from .typing import ErrorHandlerCallable
 
 DeferredSetupFunction = t.Callable[["BlueprintSetupState"], t.Callable]
 
@@ -293,7 +293,6 @@ class Blueprint(Scaffold):
             Registering the same blueprint with the same name multiple
             times is deprecated and will become an error in Flask 2.1.
         """
-        first_registration = not any(bp is self for bp in app.blueprints.values())
         name_prefix = options.get("name_prefix", "")
         self_name = options.get("name", self.name)
         name = f"{name_prefix}.{self_name}".lstrip(".")
@@ -318,9 +317,12 @@ class Blueprint(Scaffold):
                     stacklevel=4,
                 )
 
+        first_bp_registration = not any(bp is self for bp in app.blueprints.values())
+        first_name_registration = name not in app.blueprints
+
         app.blueprints[name] = self
         self._got_registered_once = True
-        state = self.make_setup_state(app, options, first_registration)
+        state = self.make_setup_state(app, options, first_bp_registration)
 
         if self.has_static_folder:
             state.add_url_rule(
@@ -330,7 +332,7 @@ class Blueprint(Scaffold):
             )
 
         # Merge blueprint data into parent.
-        if first_registration:
+        if first_bp_registration or first_name_registration:
 
             def extend(bp_dict, parent_dict):
                 for key, values in bp_dict.items():
@@ -581,7 +583,9 @@ class Blueprint(Scaffold):
         handler is used for all requests, even if outside of the blueprint.
         """
 
-        def decorator(f: ErrorHandlerCallable) -> ErrorHandlerCallable:
+        def decorator(
+            f: "ErrorHandlerCallable[Exception]",
+        ) -> "ErrorHandlerCallable[Exception]":
             self.record_once(lambda s: s.app.errorhandler(code)(f))
             return f
 

src/flask/scaffold.py

@@ -21,7 +21,7 @@ from .templating import _default_template_ctx_processor
 from .typing import AfterRequestCallable
 from .typing import AppOrBlueprintKey
 from .typing import BeforeRequestCallable
-from .typing import ErrorHandlerCallable
+from .typing import GenericException
 from .typing import TeardownCallable
 from .typing import TemplateContextProcessorCallable
 from .typing import URLDefaultCallable
@@ -29,6 +29,7 @@ from .typing import URLValuePreprocessorCallable
 
 if t.TYPE_CHECKING:
     from .wrappers import Response
+    from .typing import ErrorHandlerCallable
 
 # a singleton sentinel value for parameter defaults
 _sentinel = object()
@@ -144,7 +145,10 @@ class Scaffold:
         #: directly and its format may change at any time.
         self.error_handler_spec: t.Dict[
             AppOrBlueprintKey,
-            t.Dict[t.Optional[int], t.Dict[t.Type[Exception], ErrorHandlerCallable]],
+            t.Dict[
+                t.Optional[int],
+                t.Dict[t.Type[Exception], "ErrorHandlerCallable[Exception]"],
+            ],
         ] = defaultdict(lambda: defaultdict(dict))
 
         #: A data structure of functions to call at the beginning of
@@ -643,8 +647,11 @@ class Scaffold:
 
     @setupmethod
     def errorhandler(
-        self, code_or_exception: t.Union[t.Type[Exception], int]
+        self, code_or_exception: t.Union[t.Type[GenericException], int]
-    ) -> t.Callable[[ErrorHandlerCallable], ErrorHandlerCallable]:
+    ) -> t.Callable[
+        ["ErrorHandlerCallable[GenericException]"],
+        "ErrorHandlerCallable[GenericException]",
+    ]:
         """Register a function to handle errors by code or exception class.
 
         A decorator that is used to register a function given an
@@ -674,7 +681,9 @@ class Scaffold:
                                   an arbitrary exception
         """
 
-        def decorator(f: ErrorHandlerCallable) -> ErrorHandlerCallable:
+        def decorator(
+            f: "ErrorHandlerCallable[GenericException]",
+        ) -> "ErrorHandlerCallable[GenericException]":
             self.register_error_handler(code_or_exception, f)
             return f
 
@@ -683,8 +692,8 @@ class Scaffold:
     @setupmethod
     def register_error_handler(
         self,
-        code_or_exception: t.Union[t.Type[Exception], int],
+        code_or_exception: t.Union[t.Type[GenericException], int],
-        f: ErrorHandlerCallable,
+        f: "ErrorHandlerCallable[GenericException]",
     ) -> None:
         """Alternative error attach function to the :meth:`errorhandler`
         decorator that is more straightforward to use for non decorator
@@ -708,7 +717,9 @@ class Scaffold:
                 " instead."
             )
 
-        self.error_handler_spec[None][code][exc_class] = f
+        self.error_handler_spec[None][code][exc_class] = t.cast(
+            "ErrorHandlerCallable[Exception]", f
+        )
 
     @staticmethod
     def _get_exc_class_and_code(

src/flask/typing.py

@@ -33,11 +33,12 @@ ResponseReturnValue = t.Union[
     "WSGIApplication",
 ]
 
+GenericException = t.TypeVar("GenericException", bound=Exception, contravariant=True)
+
 AppOrBlueprintKey = t.Optional[str]  # The App key is None, whereas blueprints are named
 AfterRequestCallable = t.Callable[["Response"], "Response"]
 BeforeFirstRequestCallable = t.Callable[[], None]
 BeforeRequestCallable = t.Callable[[], t.Optional[ResponseReturnValue]]
-ErrorHandlerCallable = t.Callable[[Exception], ResponseReturnValue]
 TeardownCallable = t.Callable[[t.Optional[BaseException]], None]
 TemplateContextProcessorCallable = t.Callable[[], t.Dict[str, t.Any]]
 TemplateFilterCallable = t.Callable[..., t.Any]
@@ -45,3 +46,11 @@ TemplateGlobalCallable = t.Callable[..., t.Any]
 TemplateTestCallable = t.Callable[..., bool]
 URLDefaultCallable = t.Callable[[str, dict], None]
 URLValuePreprocessorCallable = t.Callable[[t.Optional[str], t.Optional[dict]], None]
+
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+    class ErrorHandlerCallable(te.Protocol[GenericException]):
+        def __call__(self, error: GenericException) -> ResponseReturnValue:
+            ...

src/flask/views.py

@@ -1,5 +1,6 @@
 import typing as t
 
+from .globals import current_app
 from .globals import request
 from .typing import ResponseReturnValue
 
@@ -80,7 +81,7 @@ class View:
 
         def view(*args: t.Any, **kwargs: t.Any) -> ResponseReturnValue:
             self = view.view_class(*class_args, **class_kwargs)  # type: ignore
-            return self.dispatch_request(*args, **kwargs)
+            return current_app.ensure_sync(self.dispatch_request)(*args, **kwargs)
 
         if cls.decorators:
             view.__name__ = name
@@ -154,4 +155,4 @@ class MethodView(View, metaclass=MethodViewType):
             meth = getattr(self, "get", None)
 
         assert meth is not None, f"Unimplemented method {request.method!r}"
-        return meth(*args, **kwargs)
+        return current_app.ensure_sync(meth)(*args, **kwargs)

tests/test_async.py

@@ -6,6 +6,8 @@ import pytest
 from flask import Blueprint
 from flask import Flask
 from flask import request
+from flask.views import MethodView
+from flask.views import View
 
 pytest.importorskip("asgiref")
 
@@ -18,6 +20,24 @@ class BlueprintError(Exception):
     pass
 
 
+class AsyncView(View):
+    methods = ["GET", "POST"]
+
+    async def dispatch_request(self):
+        await asyncio.sleep(0)
+        return request.method
+
+
+class AsyncMethodView(MethodView):
+    async def get(self):
+        await asyncio.sleep(0)
+        return "GET"
+
+    async def post(self):
+        await asyncio.sleep(0)
+        return "POST"
+
+
 @pytest.fixture(name="async_app")
 def _async_app():
     app = Flask(__name__)
@@ -53,11 +73,14 @@ def _async_app():
 
     app.register_blueprint(blueprint, url_prefix="/bp")
 
+    app.add_url_rule("/view", view_func=AsyncView.as_view("view"))
+    app.add_url_rule("/methodview", view_func=AsyncMethodView.as_view("methodview"))
+
     return app
 
 
 @pytest.mark.skipif(sys.version_info < (3, 7), reason="requires Python >= 3.7")
-@pytest.mark.parametrize("path", ["/", "/home", "/bp/"])
+@pytest.mark.parametrize("path", ["/", "/home", "/bp/", "/view", "/methodview"])
 def test_async_route(path, async_app):
     test_client = async_app.test_client()
     response = test_client.get(path)

tests/test_blueprints.py

@@ -899,6 +899,14 @@ def test_blueprint_renaming(app, client) -> None:
     def index():
         return flask.request.endpoint
 
+    @bp.get("/error")
+    def error():
+        flask.abort(403)
+
+    @bp.errorhandler(403)
+    def forbidden(_: Exception):
+        return "Error", 403
+
     @bp2.get("/")
     def index2():
         return flask.request.endpoint
@@ -911,3 +919,5 @@ def test_blueprint_renaming(app, client) -> None:
     assert client.get("/b/").data == b"alt.index"
     assert client.get("/a/a/").data == b"bp.sub.index2"
     assert client.get("/b/a/").data == b"alt.sub.index2"
+    assert client.get("/a/error").data == b"Error"
+    assert client.get("/b/error").data == b"Error"