From 77ff2596511efe62c9b0536107445cfe9d6846c1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Trval?= <trval@kajot.cz>
Date: Tue, 3 Oct 2023 10:34:26 +0200
Subject: [PATCH] fix: flask import of _endpoint_from_view_func is now resolved
 new util function import_check_view_func #567

---
 flask_restx/api.py   | 11 +++++------
 flask_restx/utils.py | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/flask_restx/api.py b/flask_restx/api.py
index 5996dd59..bd0413dd 100644
--- a/flask_restx/api.py
+++ b/flask_restx/api.py
@@ -14,10 +14,6 @@
 from flask import url_for, request, current_app
 from flask import make_response as original_flask_make_response
 
-try:
-    from flask.helpers import _endpoint_from_view_func
-except ImportError:
-    from flask.scaffold import _endpoint_from_view_func
 from flask.signals import got_request_exception
 
 from jsonschema import RefResolver
@@ -45,10 +41,13 @@
 from .postman import PostmanCollectionV1
 from .resource import Resource
 from .swagger import Swagger
-from .utils import default_id, camel_to_dash, unpack
+from .utils import default_id, camel_to_dash, unpack, import_check_view_func
 from .representations import output_json
 from ._http import HTTPStatus
 
+endpoint_from_view_func = import_check_view_func()
+
+
 RE_RULES = re.compile("(<.*>)")
 
 # List headers that should never be handled by Flask-RESTX
@@ -850,7 +849,7 @@ def _blueprint_setup_add_url_rule_patch(
             rule = blueprint_setup.url_prefix + rule
         options.setdefault("subdomain", blueprint_setup.subdomain)
         if endpoint is None:
-            endpoint = _endpoint_from_view_func(view_func)
+            endpoint = endpoint_from_view_func(view_func)
         defaults = blueprint_setup.url_defaults
         if "defaults" in options:
             defaults = dict(defaults, **options.pop("defaults"))
diff --git a/flask_restx/utils.py b/flask_restx/utils.py
index 809a29b3..16aa940a 100644
--- a/flask_restx/utils.py
+++ b/flask_restx/utils.py
@@ -1,4 +1,6 @@
 import re
+import warnings
+import typing
 
 from collections import OrderedDict
 from copy import deepcopy
@@ -20,6 +22,9 @@
 )
 
 
+class FlaskCompatibilityWarning(DeprecationWarning):
+    pass
+
 def merge(first, second):
     """
     Recursively merges two dictionaries.
@@ -118,3 +123,40 @@ def unpack(response, default_code=HTTPStatus.OK):
         return data, code or default_code, headers
     else:
         raise ValueError("Too many response values")
+
+
+def import_check_view_func():
+    """
+    Resolve import flask _endpoint_from_view_func.
+
+    Show warning if function cannot be found and provide copy of last known implementation.
+
+    Note: This helper method exists because reoccurring problem with flask function, but
+    actual method body remaining the same in each flask version.
+    """
+    import importlib.metadata
+    flask_version = importlib.metadata.version("flask").split(".")
+
+    def local_endpoint_from_view_func(view_func: typing.Callable) -> str:
+        """Copy of flask internal helper that returns the default endpoint for a given
+        function.  This always is the function name.
+        """
+        assert view_func is not None, "expected view func if endpoint is not provided."
+        return view_func.__name__
+    try:
+        if flask_version[0] == "1":
+            from flask.helpers import _endpoint_from_view_func
+        elif flask_version[0] == "2":
+            from flask.scaffold import _endpoint_from_view_func
+        elif flask_version[0] == "3":
+            from flask.sansio.scaffold import _endpoint_from_view_func
+        else:
+            warnings.simplefilter("once", FlaskCompatibilityWarning)
+            _endpoint_from_view_func = None
+    except ImportError:
+        warnings.simplefilter("once", FlaskCompatibilityWarning)
+        _endpoint_from_view_func = None
+    if _endpoint_from_view_func is None:
+        _endpoint_from_view_func = local_endpoint_from_view_func
+    return _endpoint_from_view_func
+