Add schema representation for plugin action error responses (#10538)

* Define error serializer and codes for schema

* Bump api version

* Update integration test status code check

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,12 +1,15 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 406
+INVENTREE_API_VERSION = 407
 
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v407 -> 2025-10-09: https://github.com/inventree/InvenTree/pull/10538
+    - Breaking: Set error status code for plugin action call instead of just returning error data
+
 v406 -> 2025-10-08: https://github.com/inventree/InvenTree/pull/10532
     - Set return type for background task overview
     - Implement serializer for part serial number detail

src/backend/InvenTree/plugin/base/action/api.py

@@ -2,7 +2,8 @@
 
 from django.utils.translation import gettext_lazy as _
 
-from rest_framework import serializers
+from drf_spectacular.utils import OpenApiResponse, extend_schema
+from rest_framework import serializers, status
 from rest_framework.generics import GenericAPIView
 from rest_framework.response import Response
 
@@ -18,12 +19,32 @@ class ActionPluginSerializer(serializers.Serializer):
     data = serializers.DictField()
 
 
+class ActionPluginErrorSerializer(serializers.Serializer):
+    """Serializer for the ActionPluginView error responses."""
+
+    error = serializers.CharField()
+    action = serializers.CharField(required=False)
+
+
 class ActionPluginView(GenericAPIView):
     """Endpoint for running custom action plugins."""
 
     permission_classes = [InvenTree.permissions.IsAuthenticatedOrReadScope]
     serializer_class = ActionPluginSerializer
 
+    @extend_schema(
+        responses={
+            200: ActionPluginSerializer,
+            400: OpenApiResponse(
+                description='No action specified',
+                response=ActionPluginErrorSerializer(),
+            ),
+            404: OpenApiResponse(
+                description='No matching action found',
+                response=ActionPluginErrorSerializer(),
+            ),
+        }
+    )
     def post(self, request, *args, **kwargs):
         """This function checks if all required info was submitted and then performs a plugin_action or returns an error."""
         action = request.data.get('action', None)
@@ -31,7 +52,9 @@ class ActionPluginView(GenericAPIView):
         data = request.data.get('data', None)
 
         if action is None:
-            return Response({'error': _('No action specified')})
+            return Response(
+                {'error': _('No action specified')}, status=status.HTTP_400_BAD_REQUEST
+            )
 
         action_plugins = registry.with_mixin(PluginMixinEnum.ACTION)
         for plugin in action_plugins:
@@ -43,4 +66,7 @@ class ActionPluginView(GenericAPIView):
                 log_error('perform_action', plugin=plugin.slug)
 
         # If we got to here, no matching action was found
-        return Response({'error': _('No matching action found'), 'action': action})
+        return Response(
+            {'error': _('No matching action found'), 'action': action},
+            status=status.HTTP_404_NOT_FOUND,
+        )

src/backend/InvenTree/plugin/base/action/test_action.py

@@ -83,12 +83,12 @@ class APITests(InvenTreeTestCase):
         """Check the possible errors with post."""
         # Test empty request
         response = self.client.post('/api/action/')
-        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.status_code, 400)
         self.assertEqual(response.data, {'error': 'No action specified'})
 
         # Test non-existing action
         response = self.client.post('/api/action/', data={'action': 'nonexisting'})
-        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.status_code, 404)
         self.assertEqual(
             response.data,
             {'error': 'No matching action found', 'action': 'nonexisting'},

src/backend/InvenTree/plugin/samples/integration/test_simpleactionplugin.py

@@ -27,7 +27,7 @@ class SimpleActionPluginTests(InvenTreeTestCase):
         self.set_plugin_state(False)
 
         response = self.client.post('/api/action/', data=data)
-        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.status_code, 404)
         self.assertIn('error', response.data)
 
         # Now enable the plugin