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from __future__ import annotations
import logging
import os
import sys
import typing as t
from datetime import timedelta
from itertools import chain
from werkzeug.exceptions import Aborter
from werkzeug.exceptions import BadRequest
from werkzeug.exceptions import BadRequestKeyError
from werkzeug.routing import BuildError
from werkzeug.routing import Map
from werkzeug.routing import Rule
from werkzeug.sansio.response import Response
from werkzeug.utils import cached_property
from werkzeug.utils import redirect as _wz_redirect
from .. import typing as ft
from ..config import Config
from ..config import ConfigAttribute
from ..ctx import _AppCtxGlobals
from ..helpers import _split_blueprint_path
from ..helpers import get_debug_flag
from ..json.provider import DefaultJSONProvider
from ..json.provider import JSONProvider
from ..logging import create_logger
from ..templating import DispatchingJinjaLoader
from ..templating import Environment
from .scaffold import _endpoint_from_view_func
from .scaffold import find_package
from .scaffold import Scaffold
from .scaffold import setupmethod
if t.TYPE_CHECKING: # pragma: no cover
from werkzeug.wrappers import Response as BaseResponse
from ..testing import FlaskClient
from ..testing import FlaskCliRunner
from .blueprints import Blueprint
T_shell_context_processor = t.TypeVar(
"T_shell_context_processor", bound=ft.ShellContextProcessorCallable
)
T_teardown = t.TypeVar("T_teardown", bound=ft.TeardownCallable)
T_template_filter = t.TypeVar("T_template_filter", bound=ft.TemplateFilterCallable)
T_template_global = t.TypeVar("T_template_global", bound=ft.TemplateGlobalCallable)
T_template_test = t.TypeVar("T_template_test", bound=ft.TemplateTestCallable)
def _make_timedelta(value: timedelta | int | None) -> timedelta | None:
if value is None or isinstance(value, timedelta):
return value
return timedelta(seconds=value)
class App(Scaffold):
"""The flask object implements a WSGI application and acts as the central
object. It is passed the name of the module or package of the
application. Once it is created it will act as a central registry for
the view functions, the URL rules, template configuration and much more.
The name of the package is used to resolve resources from inside the
package or the folder the module is contained in depending on if the
package parameter resolves to an actual python package (a folder with
an :file:`__init__.py` file inside) or a standard module (just a ``.py`` file).
For more information about resource loading, see :func:`open_resource`.
Usually you create a :class:`Flask` instance in your main module or
in the :file:`__init__.py` file of your package like this::
from flask import Flask
app = Flask(__name__)
.. admonition:: About the First Parameter
The idea of the first parameter is to give Flask an idea of what
belongs to your application. This name is used to find resources
on the filesystem, can be used by extensions to improve debugging
information and a lot more.
So it's important what you provide there. If you are using a single
module, `__name__` is always the correct value. If you however are
using a package, it's usually recommended to hardcode the name of
your package there.
For example if your application is defined in :file:`yourapplication/app.py`
you should create it with one of the two versions below::
app = Flask('yourapplication')
app = Flask(__name__.split('.')[0])
Why is that? The application will work even with `__name__`, thanks
to how resources are looked up. However it will make debugging more
painful. Certain extensions can make assumptions based on the
import name of your application. For example the Flask-SQLAlchemy
extension will look for the code in your application that triggered
an SQL query in debug mode. If the import name is not properly set
up, that debugging information is lost. (For example it would only
pick up SQL queries in `yourapplication.app` and not
`yourapplication.views.frontend`)
.. versionadded:: 0.7
The `static_url_path`, `static_folder`, and `template_folder`
parameters were added.
.. versionadded:: 0.8
The `instance_path` and `instance_relative_config` parameters were
added.
.. versionadded:: 0.11
The `root_path` parameter was added.
.. versionadded:: 1.0
The ``host_matching`` and ``static_host`` parameters were added.
.. versionadded:: 1.0
The ``subdomain_matching`` parameter was added. Subdomain
matching needs to be enabled manually now. Setting
:data:`SERVER_NAME` does not implicitly enable it.
:param import_name: the name of the application package
:param static_url_path: can be used to specify a different path for the
static files on the web. Defaults to the name
of the `static_folder` folder.
:param static_folder: The folder with static files that is served at
``static_url_path``. Relative to the application ``root_path``
or an absolute path. Defaults to ``'static'``.
:param static_host: the host to use when adding the static route.
Defaults to None. Required when using ``host_matching=True``
with a ``static_folder`` configured.
:param host_matching: set ``url_map.host_matching`` attribute.
Defaults to False.
:param subdomain_matching: consider the subdomain relative to
:data:`SERVER_NAME` when matching routes. Defaults to False.
:param template_folder: the folder that contains the templates that should
be used by the application. Defaults to
``'templates'`` folder in the root path of the
application.
:param instance_path: An alternative instance path for the application.
By default the folder ``'instance'`` next to the
package or module is assumed to be the instance
path.
:param instance_relative_config: if set to ``True`` relative filenames
for loading the config are assumed to
be relative to the instance path instead
of the application root.
:param root_path: The path to the root of the application files.
This should only be set manually when it can't be detected
automatically, such as for namespace packages.
"""
#: The class of the object assigned to :attr:`aborter`, created by
#: :meth:`create_aborter`. That object is called by
#: :func:`flask.abort` to raise HTTP errors, and can be
#: called directly as well.
#:
#: Defaults to :class:`werkzeug.exceptions.Aborter`.
#:
#: .. versionadded:: 2.2
aborter_class = Aborter
#: The class that is used for the Jinja environment.
#:
#: .. versionadded:: 0.11
jinja_environment = Environment
#: The class that is used for the :data:`~flask.g` instance.
#:
#: Example use cases for a custom class:
#:
#: 1. Store arbitrary attributes on flask.g.
#: 2. Add a property for lazy per-request database connectors.
#: 3. Return None instead of AttributeError on unexpected attributes.
#: 4. Raise exception if an unexpected attr is set, a "controlled" flask.g.
#:
#: In Flask 0.9 this property was called `request_globals_class` but it
#: was changed in 0.10 to :attr:`app_ctx_globals_class` because the
#: flask.g object is now application context scoped.
#:
#: .. versionadded:: 0.10
app_ctx_globals_class = _AppCtxGlobals
#: The class that is used for the ``config`` attribute of this app.
#: Defaults to :class:`~flask.Config`.
#:
#: Example use cases for a custom class:
#:
#: 1. Default values for certain config options.
#: 2. Access to config values through attributes in addition to keys.
#:
#: .. versionadded:: 0.11
config_class = Config
#: The testing flag. Set this to ``True`` to enable the test mode of
#: Flask extensions (and in the future probably also Flask itself).
#: For example this might activate test helpers that have an
#: additional runtime cost which should not be enabled by default.
#:
#: If this is enabled and PROPAGATE_EXCEPTIONS is not changed from the
#: default it's implicitly enabled.
#:
#: This attribute can also be configured from the config with the
#: ``TESTING`` configuration key. Defaults to ``False``.
testing = ConfigAttribute[bool]("TESTING")
#: If a secret key is set, cryptographic components can use this to
#: sign cookies and other things. Set this to a complex random value
#: when you want to use the secure cookie for instance.
#:
#: This attribute can also be configured from the config with the
#: :data:`SECRET_KEY` configuration key. Defaults to ``None``.
secret_key = ConfigAttribute[t.Union[str, bytes, None]]("SECRET_KEY")
#: A :class:`~datetime.timedelta` which is used to set the expiration
#: date of a permanent session. The default is 31 days which makes a
#: permanent session survive for roughly one month.
#:
#: This attribute can also be configured from the config with the
#: ``PERMANENT_SESSION_LIFETIME`` configuration key. Defaults to
#: ``timedelta(days=31)``
permanent_session_lifetime = ConfigAttribute[timedelta](
"PERMANENT_SESSION_LIFETIME",
get_converter=_make_timedelta, # type: ignore[arg-type]
)
json_provider_class: type[JSONProvider] = DefaultJSONProvider
"""A subclass of :class:`~flask.json.provider.JSONProvider`. An
instance is created and assigned to :attr:`app.json` when creating
the app.
The default, :class:`~flask.json.provider.DefaultJSONProvider`, uses
Python's built-in :mod:`json` library. A different provider can use
a different JSON library.
.. versionadded:: 2.2
"""
#: Options that are passed to the Jinja environment in
#: :meth:`create_jinja_environment`. Changing these options after
#: the environment is created (accessing :attr:`jinja_env`) will
#: have no effect.
#:
#: .. versionchanged:: 1.1.0
#: This is a ``dict`` instead of an ``ImmutableDict`` to allow
#: easier configuration.
#:
jinja_options: dict[str, t.Any] = {}
#: The rule object to use for URL rules created. This is used by
#: :meth:`add_url_rule`. Defaults to :class:`werkzeug.routing.Rule`.
#:
#: .. versionadded:: 0.7
url_rule_class = Rule
#: The map object to use for storing the URL rules and routing
#: configuration parameters. Defaults to :class:`werkzeug.routing.Map`.
#:
#: .. versionadded:: 1.1.0
url_map_class = Map
#: The :meth:`test_client` method creates an instance of this test
#: client class. Defaults to :class:`~flask.testing.FlaskClient`.
#:
#: .. versionadded:: 0.7
test_client_class: type[FlaskClient] | None = None
#: The :class:`~click.testing.CliRunner` subclass, by default
#: :class:`~flask.testing.FlaskCliRunner` that is used by
#: :meth:`test_cli_runner`. Its ``__init__`` method should take a
#: Flask app object as the first argument.
#:
#: .. versionadded:: 1.0
test_cli_runner_class: type[FlaskCliRunner] | None = None
default_config: dict[str, t.Any]
response_class: type[Response]
def __init__(
self,
import_name: str,
static_url_path: str | None = None,
static_folder: str | os.PathLike[str] | None = "static",
static_host: str | None = None,
host_matching: bool = False,
subdomain_matching: bool = False,
template_folder: str | os.PathLike[str] | None = "templates",
instance_path: str | None = None,
instance_relative_config: bool = False,
root_path: str | None = None,
):
super().__init__(
import_name=import_name,
static_folder=static_folder,
static_url_path=static_url_path,
template_folder=template_folder,
root_path=root_path,
)
if instance_path is None:
instance_path = self.auto_find_instance_path()
elif not os.path.isabs(instance_path):
raise ValueError(
"If an instance path is provided it must be absolute."
" A relative path was given instead."
)
#: Holds the path to the instance folder.
#:
#: .. versionadded:: 0.8
self.instance_path = instance_path
#: The configuration dictionary as :class:`Config`. This behaves
#: exactly like a regular dictionary but supports additional methods
#: to load a config from files.
self.config = self.make_config(instance_relative_config)
#: An instance of :attr:`aborter_class` created by
#: :meth:`make_aborter`. This is called by :func:`flask.abort`
#: to raise HTTP errors, and can be called directly as well.
#:
#: .. versionadded:: 2.2
#: Moved from ``flask.abort``, which calls this object.
self.aborter = self.make_aborter()
self.json: JSONProvider = self.json_provider_class(self)
"""Provides access to JSON methods. Functions in ``flask.json``
will call methods on this provider when the application context
is active. Used for handling JSON requests and responses.
An instance of :attr:`json_provider_class`. Can be customized by
changing that attribute on a subclass, or by assigning to this
attribute afterwards.
The default, :class:`~flask.json.provider.DefaultJSONProvider`,
uses Python's built-in :mod:`json` library. A different provider
can use a different JSON library.
.. versionadded:: 2.2
"""
#: A list of functions that are called by
#: :meth:`handle_url_build_error` when :meth:`.url_for` raises a
#: :exc:`~werkzeug.routing.BuildError`. Each function is called
#: with ``error``, ``endpoint`` and ``values``. If a function
#: returns ``None`` or raises a ``BuildError``, it is skipped.
#: Otherwise, its return value is returned by ``url_for``.
#:
#: .. versionadded:: 0.9
self.url_build_error_handlers: list[
t.Callable[[Exception, str, dict[str, t.Any]], str]
] = []
#: A list of functions that are called when the application context
#: is destroyed. Since the application context is also torn down
#: if the request ends this is the place to store code that disconnects
#: from databases.
#:
#: .. versionadded:: 0.9
self.teardown_appcontext_funcs: list[ft.TeardownCallable] = []
#: A list of shell context processor functions that should be run
#: when a shell context is created.
#:
#: .. versionadded:: 0.11
self.shell_context_processors: list[ft.ShellContextProcessorCallable] = []
#: Maps registered blueprint names to blueprint objects. The
#: dict retains the order the blueprints were registered in.
#: Blueprints can be registered multiple times, this dict does
#: not track how often they were attached.
#:
#: .. versionadded:: 0.7
self.blueprints: dict[str, Blueprint] = {}
#: a place where extensions can store application specific state. For
#: example this is where an extension could store database engines and
#: similar things.
#:
#: The key must match the name of the extension module. For example in
#: case of a "Flask-Foo" extension in `flask_foo`, the key would be
#: ``'foo'``.
#:
#: .. versionadded:: 0.7
self.extensions: dict[str, t.Any] = {}
#: The :class:`~werkzeug.routing.Map` for this instance. You can use
#: this to change the routing converters after the class was created
#: but before any routes are connected. Example::
#:
#: from werkzeug.routing import BaseConverter
#:
#: class ListConverter(BaseConverter):
#: def to_python(self, value):
#: return value.split(',')
#: def to_url(self, values):
#: return ','.join(super(ListConverter, self).to_url(value)
#: for value in values)
#:
#: app = Flask(__name__)
#: app.url_map.converters['list'] = ListConverter
self.url_map = self.url_map_class(host_matching=host_matching)
self.subdomain_matching = subdomain_matching
# tracks internally if the application already handled at least one
# request.
self._got_first_request = False
def _check_setup_finished(self, f_name: str) -> None:
if self._got_first_request:
raise AssertionError(
f"The setup method '{f_name}' can no longer be called"
" on the application. It has already handled its first"
" request, any changes will not be applied"
" consistently.\n"
"Make sure all imports, decorators, functions, etc."
" needed to set up the application are done before"
" running it."
)
@cached_property
def name(self) -> str: # type: ignore
"""The name of the application. This is usually the import name
with the difference that it's guessed from the run file if the
import name is main. This name is used as a display name when
Flask needs the name of the application. It can be set and overridden
to change the value.
.. versionadded:: 0.8
"""
if self.import_name == "__main__":
fn: str | None = getattr(sys.modules["__main__"], "__file__", None)
if fn is None:
return "__main__"
return os.path.splitext(os.path.basename(fn))[0]
return self.import_name
@cached_property
def logger(self) -> logging.Logger:
"""A standard Python :class:`~logging.Logger` for the app, with
the same name as :attr:`name`.
In debug mode, the logger's :attr:`~logging.Logger.level` will
be set to :data:`~logging.DEBUG`.
If there are no handlers configured, a default handler will be
added. See :doc:`/logging` for more information.
.. versionchanged:: 1.1.0
The logger takes the same name as :attr:`name` rather than
hard-coding ``"flask.app"``.
.. versionchanged:: 1.0.0
Behavior was simplified. The logger is always named
``"flask.app"``. The level is only set during configuration,
it doesn't check ``app.debug`` each time. Only one format is
used, not different ones depending on ``app.debug``. No
handlers are removed, and a handler is only added if no
handlers are already configured.
.. versionadded:: 0.3
"""
return create_logger(self)
@cached_property
def jinja_env(self) -> Environment:
"""The Jinja environment used to load templates.
The environment is created the first time this property is
accessed. Changing :attr:`jinja_options` after that will have no
effect.
"""
return self.create_jinja_environment()
def create_jinja_environment(self) -> Environment:
raise NotImplementedError()
def make_config(self, instance_relative: bool = False) -> Config:
"""Used to create the config attribute by the Flask constructor.
The `instance_relative` parameter is passed in from the constructor
of Flask (there named `instance_relative_config`) and indicates if
the config should be relative to the instance path or the root path
of the application.
.. versionadded:: 0.8
"""
root_path = self.root_path
if instance_relative:
root_path = self.instance_path
defaults = dict(self.default_config)
defaults["DEBUG"] = get_debug_flag()
return self.config_class(root_path, defaults)
def make_aborter(self) -> Aborter:
"""Create the object to assign to :attr:`aborter`. That object
is called by :func:`flask.abort` to raise HTTP errors, and can
be called directly as well.
By default, this creates an instance of :attr:`aborter_class`,
which defaults to :class:`werkzeug.exceptions.Aborter`.
.. versionadded:: 2.2
"""
return self.aborter_class()
def auto_find_instance_path(self) -> str:
"""Tries to locate the instance path if it was not provided to the
constructor of the application class. It will basically calculate
the path to a folder named ``instance`` next to your main file or
the package.
.. versionadded:: 0.8
"""
prefix, package_path = find_package(self.import_name)
if prefix is None:
return os.path.join(package_path, "instance")
return os.path.join(prefix, "var", f"{self.name}-instance")
def create_global_jinja_loader(self) -> DispatchingJinjaLoader:
"""Creates the loader for the Jinja2 environment. Can be used to
override just the loader and keeping the rest unchanged. It's
discouraged to override this function. Instead one should override
the :meth:`jinja_loader` function instead.
The global loader dispatches between the loaders of the application
and the individual blueprints.
.. versionadded:: 0.7
"""
return DispatchingJinjaLoader(self)
def select_jinja_autoescape(self, filename: str) -> bool:
"""Returns ``True`` if autoescaping should be active for the given
template name. If no template name is given, returns `True`.
.. versionchanged:: 2.2
Autoescaping is now enabled by default for ``.svg`` files.
.. versionadded:: 0.5
"""
if filename is None:
return True
return filename.endswith((".html", ".htm", ".xml", ".xhtml", ".svg"))
@property
def debug(self) -> bool:
"""Whether debug mode is enabled. When using ``flask run`` to start the
development server, an interactive debugger will be shown for unhandled
exceptions, and the server will be reloaded when code changes. This maps to the
:data:`DEBUG` config key. It may not behave as expected if set late.
**Do not enable debug mode when deploying in production.**
Default: ``False``
"""
return self.config["DEBUG"] # type: ignore[no-any-return]
@debug.setter
def debug(self, value: bool) -> None:
self.config["DEBUG"] = value
if self.config["TEMPLATES_AUTO_RELOAD"] is None:
self.jinja_env.auto_reload = value
@setupmethod
def register_blueprint(self, blueprint: Blueprint, **options: t.Any) -> None:
"""Register a :class:`~flask.Blueprint` on the application. Keyword
arguments passed to this method will override the defaults set on the
blueprint.
Calls the blueprint's :meth:`~flask.Blueprint.register` method after
recording the blueprint in the application's :attr:`blueprints`.
:param blueprint: The blueprint to register.
:param url_prefix: Blueprint routes will be prefixed with this.
:param subdomain: Blueprint routes will match on this subdomain.
:param url_defaults: Blueprint routes will use these default values for
view arguments.
:param options: Additional keyword arguments are passed to
:class:`~flask.blueprints.BlueprintSetupState`. They can be
accessed in :meth:`~flask.Blueprint.record` callbacks.
.. versionchanged:: 2.0.1
The ``name`` option can be used to change the (pre-dotted)
name the blueprint is registered with. This allows the same
blueprint to be registered multiple times with unique names
for ``url_for``.
.. versionadded:: 0.7
"""
blueprint.register(self, options)
def iter_blueprints(self) -> t.ValuesView[Blueprint]:
"""Iterates over all blueprints by the order they were registered.
.. versionadded:: 0.11
"""
return self.blueprints.values()
@setupmethod
def add_url_rule(
self,
rule: str,
endpoint: str | None = None,
view_func: ft.RouteCallable | None = None,
provide_automatic_options: bool | None = None,
**options: t.Any,
) -> None:
if endpoint is None:
endpoint = _endpoint_from_view_func(view_func) # type: ignore
options["endpoint"] = endpoint
methods = options.pop("methods", None)
# if the methods are not given and the view_func object knows its
# methods we can use that instead. If neither exists, we go with
# a tuple of only ``GET`` as default.
if methods is None:
methods = getattr(view_func, "methods", None) or ("GET",)
if isinstance(methods, str):
raise TypeError(
"Allowed methods must be a list of strings, for"
' example: @app.route(..., methods=["POST"])'
)
methods = {item.upper() for item in methods}
# Methods that should always be added
required_methods = set(getattr(view_func, "required_methods", ()))
# starting with Flask 0.8 the view_func object can disable and
# force-enable the automatic options handling.
if provide_automatic_options is None:
provide_automatic_options = getattr(
view_func, "provide_automatic_options", None
)
if provide_automatic_options is None:
if "OPTIONS" not in methods:
provide_automatic_options = True
required_methods.add("OPTIONS")
else:
provide_automatic_options = False
# Add the required methods now.
methods |= required_methods
rule_obj = self.url_rule_class(rule, methods=methods, **options)
rule_obj.provide_automatic_options = provide_automatic_options # type: ignore[attr-defined]
self.url_map.add(rule_obj)
if view_func is not None:
old_func = self.view_functions.get(endpoint)
if old_func is not None and old_func != view_func:
raise AssertionError(
"View function mapping is overwriting an existing"
f" endpoint function: {endpoint}"
)
self.view_functions[endpoint] = view_func
@setupmethod
def template_filter(
self, name: str | None = None
) -> t.Callable[[T_template_filter], T_template_filter]:
"""A decorator that is used to register custom template filter.
You can specify a name for the filter, otherwise the function
name will be used. Example::
@app.template_filter()
def reverse(s):
return s[::-1]
:param name: the optional name of the filter, otherwise the
function name will be used.
"""
def decorator(f: T_template_filter) -> T_template_filter:
self.add_template_filter(f, name=name)
return f
return decorator
@setupmethod
def add_template_filter(
self, f: ft.TemplateFilterCallable, name: str | None = None
) -> None:
"""Register a custom template filter. Works exactly like the
:meth:`template_filter` decorator.
:param name: the optional name of the filter, otherwise the
function name will be used.
"""
self.jinja_env.filters[name or f.__name__] = f
@setupmethod
def template_test(
self, name: str | None = None
) -> t.Callable[[T_template_test], T_template_test]:
"""A decorator that is used to register custom template test.
You can specify a name for the test, otherwise the function
name will be used. Example::
@app.template_test()
def is_prime(n):
if n == 2:
return True
for i in range(2, int(math.ceil(math.sqrt(n))) + 1):
if n % i == 0:
return False
return True
.. versionadded:: 0.10
:param name: the optional name of the test, otherwise the
function name will be used.
"""
def decorator(f: T_template_test) -> T_template_test:
self.add_template_test(f, name=name)
return f
return decorator
@setupmethod
def add_template_test(
self, f: ft.TemplateTestCallable, name: str | None = None
) -> None:
"""Register a custom template test. Works exactly like the
:meth:`template_test` decorator.
.. versionadded:: 0.10
:param name: the optional name of the test, otherwise the
function name will be used.
"""
self.jinja_env.tests[name or f.__name__] = f
@setupmethod
def template_global(
self, name: str | None = None
) -> t.Callable[[T_template_global], T_template_global]:
"""A decorator that is used to register a custom template global function.
You can specify a name for the global function, otherwise the function
name will be used. Example::
@app.template_global()
def double(n):
return 2 * n
.. versionadded:: 0.10
:param name: the optional name of the global function, otherwise the
function name will be used.
"""
def decorator(f: T_template_global) -> T_template_global:
self.add_template_global(f, name=name)
return f
return decorator
@setupmethod
def add_template_global(
self, f: ft.TemplateGlobalCallable, name: str | None = None
) -> None:
"""Register a custom template global function. Works exactly like the
:meth:`template_global` decorator.
.. versionadded:: 0.10
:param name: the optional name of the global function, otherwise the
function name will be used.
"""
self.jinja_env.globals[name or f.__name__] = f
@setupmethod
def teardown_appcontext(self, f: T_teardown) -> T_teardown:
"""Registers a function to be called when the application
context is popped. The application context is typically popped
after the request context for each request, at the end of CLI
commands, or after a manually pushed context ends.
.. code-block:: python
with app.app_context():
...
When the ``with`` block exits (or ``ctx.pop()`` is called), the
teardown functions are called just before the app context is
made inactive. Since a request context typically also manages an
application context it would also be called when you pop a
request context.
When a teardown function was called because of an unhandled
exception it will be passed an error object. If an
:meth:`errorhandler` is registered, it will handle the exception
and the teardown will not receive it.
Teardown functions must avoid raising exceptions. If they
execute code that might fail they must surround that code with a
``try``/``except`` block and log any errors.
The return values of teardown functions are ignored.
.. versionadded:: 0.9
"""
self.teardown_appcontext_funcs.append(f)
return f
@setupmethod
def shell_context_processor(
self, f: T_shell_context_processor
) -> T_shell_context_processor:
"""Registers a shell context processor function.
.. versionadded:: 0.11
"""
self.shell_context_processors.append(f)
return f
def _find_error_handler(
self, e: Exception, blueprints: list[str]
) -> ft.ErrorHandlerCallable | None:
"""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
class, or ``None`` if a suitable handler is not found.
"""
exc_class, code = self._get_exc_class_and_code(type(e))
names = (*blueprints, None)
for c in (code, None) if code is not None else (None,):
for name in names:
handler_map = self.error_handler_spec[name][c]
if not handler_map:
continue
for cls in exc_class.__mro__:
handler = handler_map.get(cls)
if handler is not None:
return handler
return None
def trap_http_exception(self, e: Exception) -> bool:
"""Checks if an HTTP exception should be trapped or not. By default
this will return ``False`` for all exceptions except for a bad request
key error if ``TRAP_BAD_REQUEST_ERRORS`` is set to ``True``. It
also returns ``True`` if ``TRAP_HTTP_EXCEPTIONS`` is set to ``True``.
This is called for all HTTP exceptions raised by a view function.
If it returns ``True`` for any exception the error handler for this
exception is not called and it shows up as regular exception in the
traceback. This is helpful for debugging implicitly raised HTTP
exceptions.
.. versionchanged:: 1.0
Bad request errors are not trapped by default in debug mode.
.. versionadded:: 0.8
"""
if self.config["TRAP_HTTP_EXCEPTIONS"]:
return True
trap_bad_request = self.config["TRAP_BAD_REQUEST_ERRORS"]
# if unset, trap key errors in debug mode
if (
trap_bad_request is None
and self.debug
and isinstance(e, BadRequestKeyError)
):
return True
if trap_bad_request:
return isinstance(e, BadRequest)
return False
def should_ignore_error(self, error: BaseException | None) -> bool:
"""This is called to figure out if an error should be ignored
or not as far as the teardown system is concerned. If this
function returns ``True`` then the teardown handlers will not be
passed the error.
.. versionadded:: 0.10
"""
return False
def redirect(self, location: str, code: int = 302) -> BaseResponse:
"""Create a redirect response object.
This is called by :func:`flask.redirect`, and can be called
directly as well.
:param location: The URL to redirect to.
:param code: The status code for the redirect.
.. versionadded:: 2.2
Moved from ``flask.redirect``, which calls this method.
"""
return _wz_redirect(
location,
code=code,
Response=self.response_class, # type: ignore[arg-type]
)
def inject_url_defaults(self, endpoint: str, values: dict[str, t.Any]) -> None:
"""Injects the URL defaults for the given endpoint directly into
the values dictionary passed. This is used internally and
automatically called on URL building.
.. versionadded:: 0.7
"""
names: t.Iterable[str | None] = (None,)
# url_for may be called outside a request context, parse the
# passed endpoint instead of using request.blueprints.
if "." in endpoint:
names = chain(
names, reversed(_split_blueprint_path(endpoint.rpartition(".")[0]))
)
for name in names:
if name in self.url_default_functions:
for func in self.url_default_functions[name]:
func(endpoint, values)
def handle_url_build_error(
self, error: BuildError, endpoint: str, values: dict[str, t.Any]
) -> str:
"""Called by :meth:`.url_for` if a
:exc:`~werkzeug.routing.BuildError` was raised. If this returns
a value, it will be returned by ``url_for``, otherwise the error
will be re-raised.
Each function in :attr:`url_build_error_handlers` is called with
``error``, ``endpoint`` and ``values``. If a function returns
``None`` or raises a ``BuildError``, it is skipped. Otherwise,
its return value is returned by ``url_for``.
:param error: The active ``BuildError`` being handled.
:param endpoint: The endpoint being built.
:param values: The keyword arguments passed to ``url_for``.
"""
for handler in self.url_build_error_handlers:
try:
rv = handler(error, endpoint, values)
except BuildError as e:
# make error available outside except block
error = e
else:
if rv is not None:
return rv
# Re-raise if called with an active exception, otherwise raise
# the passed in exception.
if error is sys.exc_info()[1]:
raise
raise error