190 lines
6.6 KiB
Python
190 lines
6.6 KiB
Python
from __future__ import annotations
|
|
|
|
import typing as t
|
|
|
|
from . import typing as ft
|
|
from .globals import current_app
|
|
from .globals import request
|
|
|
|
|
|
http_method_funcs = frozenset(
|
|
["get", "post", "head", "options", "delete", "put", "trace", "patch"]
|
|
)
|
|
|
|
|
|
class View:
|
|
"""Subclass this class and override :meth:`dispatch_request` to
|
|
create a generic class-based view. Call :meth:`as_view` to create a
|
|
view function that creates an instance of the class with the given
|
|
arguments and calls its ``dispatch_request`` method with any URL
|
|
variables.
|
|
|
|
See :doc:`views` for a detailed guide.
|
|
|
|
.. code-block:: python
|
|
|
|
class Hello(View):
|
|
init_every_request = False
|
|
|
|
def dispatch_request(self, name):
|
|
return f"Hello, {name}!"
|
|
|
|
app.add_url_rule(
|
|
"/hello/<name>", view_func=Hello.as_view("hello")
|
|
)
|
|
|
|
Set :attr:`methods` on the class to change what methods the view
|
|
accepts.
|
|
|
|
Set :attr:`decorators` on the class to apply a list of decorators to
|
|
the generated view function. Decorators applied to the class itself
|
|
will not be applied to the generated view function!
|
|
|
|
Set :attr:`init_every_request` to ``False`` for efficiency, unless
|
|
you need to store request-global data on ``self``.
|
|
"""
|
|
|
|
#: The methods this view is registered for. Uses the same default
|
|
#: (``["GET", "HEAD", "OPTIONS"]``) as ``route`` and
|
|
#: ``add_url_rule`` by default.
|
|
methods: t.ClassVar[t.Collection[str] | None] = None
|
|
|
|
#: Control whether the ``OPTIONS`` method is handled automatically.
|
|
#: Uses the same default (``True``) as ``route`` and
|
|
#: ``add_url_rule`` by default.
|
|
provide_automatic_options: t.ClassVar[bool | None] = None
|
|
|
|
#: A list of decorators to apply, in order, to the generated view
|
|
#: function. Remember that ``@decorator`` syntax is applied bottom
|
|
#: to top, so the first decorator in the list would be the bottom
|
|
#: decorator.
|
|
#:
|
|
#: .. versionadded:: 0.8
|
|
decorators: t.ClassVar[list[t.Callable]] = []
|
|
|
|
#: Create a new instance of this view class for every request by
|
|
#: default. If a view subclass sets this to ``False``, the same
|
|
#: instance is used for every request.
|
|
#:
|
|
#: A single instance is more efficient, especially if complex setup
|
|
#: is done during init. However, storing data on ``self`` is no
|
|
#: longer safe across requests, and :data:`~flask.g` should be used
|
|
#: instead.
|
|
#:
|
|
#: .. versionadded:: 2.2
|
|
init_every_request: t.ClassVar[bool] = True
|
|
|
|
def dispatch_request(self) -> ft.ResponseReturnValue:
|
|
"""The actual view function behavior. Subclasses must override
|
|
this and return a valid response. Any variables from the URL
|
|
rule are passed as keyword arguments.
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
@classmethod
|
|
def as_view(
|
|
cls, name: str, *class_args: t.Any, **class_kwargs: t.Any
|
|
) -> ft.RouteCallable:
|
|
"""Convert the class into a view function that can be registered
|
|
for a route.
|
|
|
|
By default, the generated view will create a new instance of the
|
|
view class for every request and call its
|
|
:meth:`dispatch_request` method. If the view class sets
|
|
:attr:`init_every_request` to ``False``, the same instance will
|
|
be used for every request.
|
|
|
|
Except for ``name``, all other arguments passed to this method
|
|
are forwarded to the view class ``__init__`` method.
|
|
|
|
.. versionchanged:: 2.2
|
|
Added the ``init_every_request`` class attribute.
|
|
"""
|
|
if cls.init_every_request:
|
|
|
|
def view(**kwargs: t.Any) -> ft.ResponseReturnValue:
|
|
self = view.view_class( # type: ignore[attr-defined]
|
|
*class_args, **class_kwargs
|
|
)
|
|
return current_app.ensure_sync(self.dispatch_request)(**kwargs)
|
|
|
|
else:
|
|
self = cls(*class_args, **class_kwargs)
|
|
|
|
def view(**kwargs: t.Any) -> ft.ResponseReturnValue:
|
|
return current_app.ensure_sync(self.dispatch_request)(**kwargs)
|
|
|
|
if cls.decorators:
|
|
view.__name__ = name
|
|
view.__module__ = cls.__module__
|
|
for decorator in cls.decorators:
|
|
view = decorator(view)
|
|
|
|
# We attach the view class to the view function for two reasons:
|
|
# first of all it allows us to easily figure out what class-based
|
|
# view this thing came from, secondly it's also used for instantiating
|
|
# the view class so you can actually replace it with something else
|
|
# for testing purposes and debugging.
|
|
view.view_class = cls # type: ignore
|
|
view.__name__ = name
|
|
view.__doc__ = cls.__doc__
|
|
view.__module__ = cls.__module__
|
|
view.methods = cls.methods # type: ignore
|
|
view.provide_automatic_options = cls.provide_automatic_options # type: ignore
|
|
return view
|
|
|
|
|
|
class MethodView(View):
|
|
"""Dispatches request methods to the corresponding instance methods.
|
|
For example, if you implement a ``get`` method, it will be used to
|
|
handle ``GET`` requests.
|
|
|
|
This can be useful for defining a REST API.
|
|
|
|
:attr:`methods` is automatically set based on the methods defined on
|
|
the class.
|
|
|
|
See :doc:`views` for a detailed guide.
|
|
|
|
.. code-block:: python
|
|
|
|
class CounterAPI(MethodView):
|
|
def get(self):
|
|
return str(session.get("counter", 0))
|
|
|
|
def post(self):
|
|
session["counter"] = session.get("counter", 0) + 1
|
|
return redirect(url_for("counter"))
|
|
|
|
app.add_url_rule(
|
|
"/counter", view_func=CounterAPI.as_view("counter")
|
|
)
|
|
"""
|
|
|
|
def __init_subclass__(cls, **kwargs: t.Any) -> None:
|
|
super().__init_subclass__(**kwargs)
|
|
|
|
if "methods" not in cls.__dict__:
|
|
methods = set()
|
|
|
|
for base in cls.__bases__:
|
|
if getattr(base, "methods", None):
|
|
methods.update(base.methods) # type: ignore[attr-defined]
|
|
|
|
for key in http_method_funcs:
|
|
if hasattr(cls, key):
|
|
methods.add(key.upper())
|
|
|
|
if methods:
|
|
cls.methods = methods
|
|
|
|
def dispatch_request(self, **kwargs: t.Any) -> ft.ResponseReturnValue:
|
|
meth = getattr(self, request.method.lower(), None)
|
|
|
|
# If the request method is HEAD and we don't have a handler for it
|
|
# retry with GET.
|
|
if meth is None and request.method == "HEAD":
|
|
meth = getattr(self, "get", None)
|
|
|
|
assert meth is not None, f"Unimplemented method {request.method!r}"
|
|
return current_app.ensure_sync(meth)(**kwargs)
|