439 lines
14 KiB
Python
439 lines
14 KiB
Python
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import contextvars
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import sys
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import typing as t
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from functools import update_wrapper
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from types import TracebackType
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from werkzeug.exceptions import HTTPException
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from . import typing as ft
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from .globals import _cv_app
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from .globals import _cv_request
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from .signals import appcontext_popped
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from .signals import appcontext_pushed
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if t.TYPE_CHECKING: # pragma: no cover
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from .app import Flask
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from .sessions import SessionMixin
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from .wrappers import Request
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# a singleton sentinel value for parameter defaults
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_sentinel = object()
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class _AppCtxGlobals:
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"""A plain object. Used as a namespace for storing data during an
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application context.
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Creating an app context automatically creates this object, which is
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made available as the :data:`g` proxy.
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.. describe:: 'key' in g
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Check whether an attribute is present.
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.. versionadded:: 0.10
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.. describe:: iter(g)
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Return an iterator over the attribute names.
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.. versionadded:: 0.10
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"""
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# Define attr methods to let mypy know this is a namespace object
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# that has arbitrary attributes.
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def __getattr__(self, name: str) -> t.Any:
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try:
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return self.__dict__[name]
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except KeyError:
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raise AttributeError(name) from None
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def __setattr__(self, name: str, value: t.Any) -> None:
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self.__dict__[name] = value
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def __delattr__(self, name: str) -> None:
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try:
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del self.__dict__[name]
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except KeyError:
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raise AttributeError(name) from None
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def get(self, name: str, default: t.Optional[t.Any] = None) -> t.Any:
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"""Get an attribute by name, or a default value. Like
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:meth:`dict.get`.
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:param name: Name of attribute to get.
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:param default: Value to return if the attribute is not present.
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.. versionadded:: 0.10
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"""
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return self.__dict__.get(name, default)
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def pop(self, name: str, default: t.Any = _sentinel) -> t.Any:
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"""Get and remove an attribute by name. Like :meth:`dict.pop`.
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:param name: Name of attribute to pop.
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:param default: Value to return if the attribute is not present,
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instead of raising a ``KeyError``.
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.. versionadded:: 0.11
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"""
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if default is _sentinel:
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return self.__dict__.pop(name)
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else:
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return self.__dict__.pop(name, default)
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def setdefault(self, name: str, default: t.Any = None) -> t.Any:
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"""Get the value of an attribute if it is present, otherwise
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set and return a default value. Like :meth:`dict.setdefault`.
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:param name: Name of attribute to get.
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:param default: Value to set and return if the attribute is not
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present.
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.. versionadded:: 0.11
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"""
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return self.__dict__.setdefault(name, default)
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def __contains__(self, item: str) -> bool:
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return item in self.__dict__
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def __iter__(self) -> t.Iterator[str]:
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return iter(self.__dict__)
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def __repr__(self) -> str:
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ctx = _cv_app.get(None)
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if ctx is not None:
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return f"<flask.g of '{ctx.app.name}'>"
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return object.__repr__(self)
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def after_this_request(f: ft.AfterRequestCallable) -> ft.AfterRequestCallable:
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"""Executes a function after this request. This is useful to modify
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response objects. The function is passed the response object and has
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to return the same or a new one.
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Example::
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@app.route('/')
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def index():
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@after_this_request
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def add_header(response):
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response.headers['X-Foo'] = 'Parachute'
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return response
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return 'Hello World!'
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This is more useful if a function other than the view function wants to
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modify a response. For instance think of a decorator that wants to add
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some headers without converting the return value into a response object.
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.. versionadded:: 0.9
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"""
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ctx = _cv_request.get(None)
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if ctx is None:
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raise RuntimeError(
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"'after_this_request' can only be used when a request"
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" context is active, such as in a view function."
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)
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ctx._after_request_functions.append(f)
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return f
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def copy_current_request_context(f: t.Callable) -> t.Callable:
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"""A helper function that decorates a function to retain the current
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request context. This is useful when working with greenlets. The moment
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the function is decorated a copy of the request context is created and
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then pushed when the function is called. The current session is also
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included in the copied request context.
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Example::
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import gevent
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from flask import copy_current_request_context
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@app.route('/')
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def index():
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@copy_current_request_context
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def do_some_work():
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# do some work here, it can access flask.request or
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# flask.session like you would otherwise in the view function.
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...
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gevent.spawn(do_some_work)
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return 'Regular response'
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.. versionadded:: 0.10
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"""
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ctx = _cv_request.get(None)
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if ctx is None:
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raise RuntimeError(
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"'copy_current_request_context' can only be used when a"
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" request context is active, such as in a view function."
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)
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ctx = ctx.copy()
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def wrapper(*args, **kwargs):
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with ctx:
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return ctx.app.ensure_sync(f)(*args, **kwargs)
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return update_wrapper(wrapper, f)
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def has_request_context() -> bool:
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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, you may want to take advantage
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of request information if the request object is available, but fail
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silently if it 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 _cv_request.get(None) is not None
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def has_app_context() -> bool:
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"""Works like :func:`has_request_context` but for the application
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context. You can also just do a boolean check on the
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:data:`current_app` object instead.
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.. versionadded:: 0.9
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"""
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return _cv_app.get(None) is not None
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class AppContext:
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"""The app context contains application-specific information. An app
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context is created and pushed at the beginning of each request if
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one is not already active. An app context is also pushed when
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running CLI commands.
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"""
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def __init__(self, app: "Flask") -> None:
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self.app = app
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self.url_adapter = app.create_url_adapter(None)
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self.g: _AppCtxGlobals = app.app_ctx_globals_class()
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self._cv_tokens: t.List[contextvars.Token] = []
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def push(self) -> None:
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"""Binds the app context to the current context."""
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self._cv_tokens.append(_cv_app.set(self))
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appcontext_pushed.send(self.app)
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def pop(self, exc: t.Optional[BaseException] = _sentinel) -> None: # type: ignore
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"""Pops the app context."""
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try:
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if len(self._cv_tokens) == 1:
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if exc is _sentinel:
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exc = sys.exc_info()[1]
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self.app.do_teardown_appcontext(exc)
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finally:
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ctx = _cv_app.get()
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_cv_app.reset(self._cv_tokens.pop())
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if ctx is not self:
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raise AssertionError(
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f"Popped wrong app context. ({ctx!r} instead of {self!r})"
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)
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appcontext_popped.send(self.app)
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def __enter__(self) -> "AppContext":
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self.push()
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return self
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def __exit__(
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self,
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exc_type: t.Optional[type],
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exc_value: t.Optional[BaseException],
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tb: t.Optional[TracebackType],
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) -> None:
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self.pop(exc_value)
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class RequestContext:
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"""The request context contains per-request information. The Flask
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app creates and pushes it at the beginning of the request, then pops
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it at the end of the request. It will create the URL adapter and
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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
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request. When using the interactive debugger, the context will be
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restored so ``request`` is still accessible. Similarly, the test
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client can preserve the context after the request ends. However,
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teardown functions may already have closed some resources such as
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database connections.
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"""
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def __init__(
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self,
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app: "Flask",
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environ: dict,
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request: t.Optional["Request"] = None,
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session: t.Optional["SessionMixin"] = None,
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) -> None:
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self.app = app
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if request is None:
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request = app.request_class(environ)
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request.json_module = app.json # type: ignore[misc]
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self.request: Request = request
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self.url_adapter = None
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try:
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self.url_adapter = app.create_url_adapter(self.request)
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except HTTPException as e:
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self.request.routing_exception = e
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self.flashes: t.Optional[t.List[t.Tuple[str, str]]] = None
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self.session: t.Optional["SessionMixin"] = session
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# Functions that should be executed after the request on the response
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# object. These will be called before the regular "after_request"
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# functions.
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self._after_request_functions: t.List[ft.AfterRequestCallable] = []
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self._cv_tokens: t.List[t.Tuple[contextvars.Token, t.Optional[AppContext]]] = []
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def copy(self) -> "RequestContext":
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"""Creates a copy of this request context with the same request object.
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This can be used to move a request context to a different greenlet.
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Because the actual request object is the same this cannot be used to
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move a request context to a different thread unless access to the
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request object is locked.
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.. versionadded:: 0.10
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.. versionchanged:: 1.1
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The current session object is used instead of reloading the original
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data. This prevents `flask.session` pointing to an out-of-date object.
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"""
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return self.__class__(
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self.app,
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environ=self.request.environ,
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request=self.request,
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session=self.session,
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)
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def match_request(self) -> None:
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"""Can be overridden by a subclass to hook into the matching
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of the request.
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"""
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try:
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result = self.url_adapter.match(return_rule=True) # type: ignore
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self.request.url_rule, self.request.view_args = result # type: ignore
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except HTTPException as e:
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self.request.routing_exception = e
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def push(self) -> None:
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# Before we push the request context we have to ensure that there
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# is an application context.
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app_ctx = _cv_app.get(None)
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if app_ctx is None or app_ctx.app is not self.app:
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app_ctx = self.app.app_context()
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app_ctx.push()
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else:
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app_ctx = None
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self._cv_tokens.append((_cv_request.set(self), app_ctx))
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# Open the session at the moment that the request context is available.
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# This allows a custom open_session method to use the request context.
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# Only open a new session if this is the first time the request was
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# pushed, otherwise stream_with_context loses the session.
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if self.session is None:
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session_interface = self.app.session_interface
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self.session = session_interface.open_session(self.app, self.request)
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if self.session is None:
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self.session = session_interface.make_null_session(self.app)
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# Match the request URL after loading the session, so that the
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# session is available in custom URL converters.
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if self.url_adapter is not None:
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self.match_request()
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def pop(self, exc: t.Optional[BaseException] = _sentinel) -> None: # type: ignore
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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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.. versionchanged:: 0.9
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Added the `exc` argument.
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"""
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clear_request = len(self._cv_tokens) == 1
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try:
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if clear_request:
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if exc is _sentinel:
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exc = sys.exc_info()[1]
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self.app.do_teardown_request(exc)
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request_close = getattr(self.request, "close", None)
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if request_close is not None:
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request_close()
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finally:
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ctx = _cv_request.get()
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token, app_ctx = self._cv_tokens.pop()
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_cv_request.reset(token)
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# get rid of circular dependencies at the end of the request
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# so that we don't require the GC to be active.
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if clear_request:
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ctx.request.environ["werkzeug.request"] = None
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if app_ctx is not None:
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app_ctx.pop(exc)
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if ctx is not self:
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raise AssertionError(
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f"Popped wrong request context. ({ctx!r} instead of {self!r})"
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)
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def __enter__(self) -> "RequestContext":
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self.push()
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return self
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def __exit__(
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self,
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exc_type: t.Optional[type],
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exc_value: t.Optional[BaseException],
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tb: t.Optional[TracebackType],
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) -> None:
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self.pop(exc_value)
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def __repr__(self) -> str:
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return (
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f"<{type(self).__name__} {self.request.url!r}"
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f" [{self.request.method}] of {self.app.name}>"
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)
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