add url_for method to app

src/flask/app.py

@@ -23,6 +23,7 @@ from werkzeug.routing import MapAdapter
 from werkzeug.routing import RequestRedirect
 from werkzeug.routing import RoutingException
 from werkzeug.routing import Rule
+from werkzeug.urls import url_quote
 from werkzeug.utils import redirect as _wz_redirect
 from werkzeug.wrappers import Response as BaseResponse
 
@@ -1661,6 +1662,50 @@ class Flask(Scaffold):
 
         return asgiref_async_to_sync(func)
 
+    def url_for(
+        self,
+        endpoint: str,
+        external: bool,
+        url_adapter,
+        **values: t.Any,
+    ) -> str:
+
+        anchor = values.pop("_anchor", None)
+        method = values.pop("_method", None)
+        scheme = values.pop("_scheme", None)
+        self.inject_url_defaults(endpoint, values)
+
+        # This is not the best way to deal with this but currently the
+        # underlying Werkzeug router does not support overriding the scheme on
+        # a per build call basis.
+        old_scheme = None
+        if scheme is not None:
+            if not external:
+                raise ValueError("When specifying _scheme, _external must be True")
+            old_scheme = url_adapter.url_scheme
+            url_adapter.url_scheme = scheme
+
+        try:
+            try:
+                rv = url_adapter.build(
+                    endpoint, values, method=method, force_external=external
+                )
+            finally:
+                if old_scheme is not None:
+                    url_adapter.url_scheme = old_scheme
+        except BuildError as error:
+            # We need to inject the values again so that the app callback can
+            # deal with that sort of stuff.
+            values["_external"] = external
+            values["_anchor"] = anchor
+            values["_method"] = method
+            values["_scheme"] = scheme
+            return self.handle_url_build_error(error, endpoint, values)
+
+        if anchor is not None:
+            rv += f"#{url_quote(anchor)}"
+        return rv
+
     def redirect(self, location: str, code: int = 302) -> BaseResponse:
         """Create a redirect response object.
 

src/flask/helpers.py

@@ -11,8 +11,6 @@ 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
 
 from .globals import _app_ctx_stack
@@ -307,41 +305,7 @@ def url_for(endpoint: str, **values: t.Any) -> str:
 
         external = values.pop("_external", True)
 
-    anchor = values.pop("_anchor", None)
+    return current_app.url_for(endpoint, external, url_adapter, **values)
-    method = values.pop("_method", None)
-    scheme = values.pop("_scheme", None)
-    appctx.app.inject_url_defaults(endpoint, values)
-
-    # This is not the best way to deal with this but currently the
-    # underlying Werkzeug router does not support overriding the scheme on
-    # a per build call basis.
-    old_scheme = None
-    if scheme is not None:
-        if not external:
-            raise ValueError("When specifying _scheme, _external must be True")
-        old_scheme = url_adapter.url_scheme
-        url_adapter.url_scheme = scheme
-
-    try:
-        try:
-            rv = url_adapter.build(
-                endpoint, values, method=method, force_external=external
-            )
-        finally:
-            if old_scheme is not None:
-                url_adapter.url_scheme = old_scheme
-    except BuildError as error:
-        # We need to inject the values again so that the app callback can
-        # deal with that sort of stuff.
-        values["_external"] = external
-        values["_anchor"] = anchor
-        values["_method"] = method
-        values["_scheme"] = scheme
-        return appctx.app.handle_url_build_error(error, endpoint, values)
-
-    if anchor is not None:
-        rv += f"#{url_quote(anchor)}"
-    return rv
 
 
 def redirect(