mitigate DRF bug in ObtainAuthToken < 3.12.0 #796

drf_spectacular/contrib/__init__.py

@@ -2,6 +2,7 @@
     'django_oauth_toolkit',
     'djangorestframework_camel_case',
     'rest_auth',
+    'rest_framework',
     'rest_polymorphic',
     'rest_framework_dataclasses',
     'rest_framework_jwt',

drf_spectacular/contrib/rest_framework.py

@@ -0,0 +1,32 @@
+from drf_spectacular.extensions import OpenApiViewExtension
+
+
+class ObtainAuthTokenView(OpenApiViewExtension):
+    target_class = 'rest_framework.authtoken.views.ObtainAuthToken'
+    match_subclasses = True
+
+    def view_replacement(self):
+        """
+        Prior to DRF 3.12.0, usage of ObtainAuthToken resulted in AssertionError
+
+            Incompatible AutoSchema used on View "ObtainAuthToken". Is DRF's DEFAULT_SCHEMA_CLASS ...
+
+        This is because DRF had a bug which made it NOT honor DEFAULT_SCHEMA_CLASS and instead
+        injected an unsolicited coreschema class for this view and this view only. This extension
+        fixes the view before the wrong schema class is used.
+
+        Bug in DRF that was fixed in later versions:
+        https://github.com/encode/django-rest-framework/blob/4121b01b912668c049b26194a9a107c27a332429/rest_framework/authtoken/views.py#L16
+        """
+        from rest_framework import VERSION
+
+        from drf_spectacular.openapi import AutoSchema
+
+        # no intervention needed
+        if VERSION >= '3.12':
+            return self.target
+
+        class FixedObtainAuthToken(self.target):
+            schema = AutoSchema()
+
+        return FixedObtainAuthToken

tests/test_regressions.py

@@ -2886,3 +2886,9 @@ def view_func(request, format=None):
         'type': 'string',
         'format': 'regex'
     }
+
+
+def test_drf_authtoken_schema_override_bug(no_warnings):
+    from rest_framework.authtoken.views import ObtainAuthToken
+
+    generate_schema('/token/', view=ObtainAuthToken)