fix: flask import of _endpoint_from_view_func - issue #567 (#572)

* fix: flask import of _endpoint_from_view_func is now resolved new util function import_check_view_func #567

* modify: include new import_check_view_func in utils.__all__ to keep nice static checks

* modify: rever changelog

* fix: test for name match

* modify: changelog - scafold import fix #567

---------

Co-authored-by: Tomáš Trval <trval@kajot.cz>

Author: Ryu-CZ

CHANGELOG.rst

@@ -25,6 +25,18 @@ Releases prior to 0.3.0 were “best effort” filled out, but are missing
 some info. If you see your contribution missing info, please open a PR
 on the Changelog!
 
+.. _section-1.2.1:
+1.2.1
+-----
+.. _bug_fixes-1.2.1
+Bug Fixes
+~~~~~~~~~
+
+::
+
+   * Fixing flask 3.0+ compatibility of `ModuleNotFoundError: No module named 'flask.scaffold'` Import error. (#567) [Ryu-CZ]
+
+
 .. _section-1.2.0:
 1.2.0
 -----

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"))

flask_restx/utils.py

@@ -1,4 +1,6 @@
 import re
+import warnings
+import typing
 
 from collections import OrderedDict
 from copy import deepcopy
@@ -17,9 +19,14 @@
     "not_none",
     "not_none_sorted",
     "unpack",
+    "import_check_view_func",
 )
 
 
+class FlaskCompatibilityWarning(DeprecationWarning):
+    pass
+
+
 def merge(first, second):
     """
     Recursively merges two dictionaries.
@@ -118,3 +125,43 @@ def unpack(response, default_code=HTTPStatus.OK):
         return data, code or default_code, headers
     else:
         raise ValueError("Too many response values")
+
+
+def to_view_name(view_func: typing.Callable) -> str:
+    """Helper that returns the default endpoint for a given
+    function. This always is the function name.
+
+    Note: copy of simple flask internal helper
+    """
+    assert view_func is not None, "expected view func if endpoint is not provided."
+    return view_func.__name__
+
+
+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(".")
+    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 = to_view_name
+    return _endpoint_from_view_func

tests/test_utils.py

@@ -98,3 +98,17 @@ def test_value_headers_default_code(self):
     def test_too_many_values(self):
         with pytest.raises(ValueError):
             utils.unpack((None, None, None, None))
+
+
+class ToViewNameTest(object):
+    def test_none(self):
+        with pytest.raises(AssertionError):
+            _ = utils.to_view_name(None)
+
+    def test_name(self):
+        assert utils.to_view_name(self.test_none) == self.test_none.__name__
+
+
+class ImportCheckViewFuncTest(object):
+    def test_callable(self):
+        assert callable(utils.import_check_view_func())