add aborter object to app

CHANGES.rst

@@ -5,6 +5,10 @@ Version 2.2.0
 
 Unreleased
 
+-   Add ``aborter_class`` and ``aborter`` attributes to the Flask app
+    object. ``flask.abort`` will call ``app.aborter``. This makes it
+    possible for an app to override how aborts work, including custom
+    status codes. :issue:`4567`
 -   Add an ``app.redirect`` method, which ``flask.redirect`` will call.
     This makes it possible for an app to override how redirects work.
     :issue:`4569`

src/flask/__init__.py

@@ -1,6 +1,5 @@
 from markupsafe import escape
 from markupsafe import Markup
-from werkzeug.exceptions import abort as abort
 
 from . import json as json
 from .app import Flask as Flask
@@ -18,6 +17,7 @@ from .globals import current_app as current_app
 from .globals import g as g
 from .globals import request as request
 from .globals import session as session
+from .helpers import abort as abort
 from .helpers import flash as flash
 from .helpers import get_flashed_messages as get_flashed_messages
 from .helpers import get_template_attribute as get_template_attribute

src/flask/app.py

@@ -12,6 +12,7 @@ from types import TracebackType
 
 from werkzeug.datastructures import Headers
 from werkzeug.datastructures import ImmutableDict
+from werkzeug.exceptions import Aborter
 from werkzeug.exceptions import BadRequest
 from werkzeug.exceptions import BadRequestKeyError
 from werkzeug.exceptions import HTTPException
@@ -201,6 +202,16 @@ class Flask(Scaffold):
     #: :class:`~flask.Response` for more information.
     response_class = Response
 
+    #: 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
@@ -421,6 +432,13 @@ class Flask(Scaffold):
         #: 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
+        self.aborter = self.make_aborter()
+
         #: A list of functions that are called when :meth:`url_for` raises a
         #: :exc:`~werkzeug.routing.BuildError`.  Each function registered here
         #: is called with `error`, `endpoint` and `values`.  If a function
@@ -628,6 +646,18 @@ class Flask(Scaffold):
         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

src/flask/helpers.py

@@ -10,6 +10,7 @@ from functools import update_wrapper
 from threading import RLock
 
 import werkzeug.utils
+from werkzeug.exceptions import abort as _wz_abort
 from werkzeug.routing import BuildError
 from werkzeug.urls import url_quote
 from werkzeug.utils import redirect as _wz_redirect
@@ -24,6 +25,7 @@ from .signals import message_flashed
 if t.TYPE_CHECKING:  # pragma: no cover
     from werkzeug.wrappers import Response as BaseResponse
     from .wrappers import Response
+    import typing_extensions as te
 
 
 def get_env() -> str:
@@ -364,6 +366,31 @@ def redirect(
     return _wz_redirect(location, code=code, Response=Response)
 
 
+def abort(  # type: ignore[misc]
+    code: t.Union[int, "BaseResponse"], *args: t.Any, **kwargs: t.Any
+) -> "te.NoReturn":
+    """Raise an :exc:`~werkzeug.exceptions.HTTPException` for the given
+    status code.
+
+    If :data:`~flask.current_app` is available, it will call its
+    :attr:`~flask.Flask.aborter` object, otherwise it will use
+    :func:`werkzeug.exceptions.abort`.
+
+    :param code: The status code for the exception, which must be
+        registered in ``app.aborter``.
+    :param args: Passed to the exception.
+    :param kwargs: Passed to the exception.
+
+    .. versionadded:: 2.2
+        Calls ``current_app.aborter`` if available instead of always
+        using Werkzeug's default ``abort``.
+    """
+    if current_app:
+        current_app.aborter(code, *args, **kwargs)
+
+    _wz_abort(code, *args, **kwargs)
+
+
 def get_template_attribute(template_name: str, attribute: str) -> t.Any:
     """Loads a macro (or variable) a template exports.  This can be used to
     invoke a macro from within Python code.  If you for example have a

tests/test_helpers.py

@@ -2,6 +2,7 @@ import io
 import os
 
 import pytest
+import werkzeug.exceptions
 
 import flask
 from flask.helpers import get_debug_flag
@@ -174,6 +175,35 @@ def test_redirect_with_app(app):
         flask.redirect("other")
 
 
+def test_abort_no_app():
+    with pytest.raises(werkzeug.exceptions.Unauthorized):
+        flask.abort(401)
+
+    with pytest.raises(LookupError):
+        flask.abort(900)
+
+
+def test_app_aborter_class():
+    class MyAborter(werkzeug.exceptions.Aborter):
+        pass
+
+    class MyFlask(flask.Flask):
+        aborter_class = MyAborter
+
+    app = MyFlask(__name__)
+    assert isinstance(app.aborter, MyAborter)
+
+
+def test_abort_with_app(app):
+    class My900Error(werkzeug.exceptions.HTTPException):
+        code = 900
+
+    app.aborter.mapping[900] = My900Error
+
+    with app.app_context(), pytest.raises(My900Error):
+        flask.abort(900)
+
+
 class TestNoImports:
     """Test Flasks are created without import.