UN-4128 [FIX] Stop the pipeline/ETL list page from 500ing

backend/pipeline_v2/serializers/crud.py

@@ -63,7 +63,8 @@ def get_fields(self) -> dict[str, Any]:
         # An update resends the bound workflow unchanged, so keep it
         # selectable: a co-owner of this resource need not own the workflow.
         # ``validate_workflow`` still refuses an actual change.
-        if self.instance is not None:
+        if isinstance(self.instance, Pipeline):
+            # On a list request, ``self.instance`` is the whole queryset, not one row.
             queryset = queryset | Workflow.objects.filter(pk=self.instance.workflow_id)
         fields["workflow"].queryset = queryset
         # Same code, readable text: the default names a pk the user never

backend/pipeline_v2/tests/test_pipeline_serializer_list_scoping.py

@@ -0,0 +1,62 @@
+"""``PipelineSerializer.get_fields`` must survive a list request.
+
+DRF's ``many_init`` builds the child serializer with the same ``instance``
+argument handed to the list serializer, so a paginated GET binds the page (a
+``list``) to the child's ``self.instance`` -- never a single ``Pipeline``.
+``get_fields`` used to guard its workflow-scoping merge with
+``self.instance is not None``, which is true for that list too, so it called
+``.workflow_id`` on a ``list`` and crashed every pipeline/ETL list request
+with an ``AttributeError``. The guard now checks ``isinstance(self.instance,
+Pipeline)`` instead.
+
+The real module is imported and its collaborator patched (Django is loaded by
+the rig's test env), so no database is touched and this stays in the unit
+tier.
+"""
+
+from __future__ import annotations
+
+import uuid
+from unittest.mock import MagicMock, patch
+
+from pipeline_v2.models import Pipeline
+from pipeline_v2.serializers.crud import PipelineSerializer
+from workflow_manager.workflow_v2.models.workflow import Workflow
+
+MUTABLE_WORKFLOWS_PATH = "pipeline_v2.serializers.crud.mutable_workflows_for"
+
+
+class TestWorkflowFieldScopingSurvivesAList:
+    """The instance-type guard in ``get_fields`` must not crash on a list."""
+
+    def test_list_instance_does_not_crash(self) -> None:
+        """A paginated list's ``self.instance`` is a ``list``, not a ``Pipeline``."""
+        serializer = PipelineSerializer()
+        serializer.instance = [MagicMock(spec=Pipeline)]
+
+        with patch(MUTABLE_WORKFLOWS_PATH, return_value=Workflow.objects.none()):
+            fields = serializer.get_fields()  # must not raise AttributeError
+
+        assert "workflow" in fields
+
+    def test_many_true_construction_does_not_crash(self) -> None:
+        """The public ``PipelineSerializer(queryset, many=True)`` entry point."""
+        with patch(MUTABLE_WORKFLOWS_PATH, return_value=Workflow.objects.none()):
+            serializer = PipelineSerializer([MagicMock(spec=Pipeline)], many=True)
+            fields = serializer.child.fields  # must not raise AttributeError
+
+        assert "workflow" in fields
+
+    def test_single_instance_still_scopes_to_its_own_workflow(self) -> None:
+        """A detail/update request keeps the co-owner carve-out for its own workflow."""
+        pipeline = MagicMock(spec=Pipeline, workflow_id=uuid.uuid4())
+        serializer = PipelineSerializer()
+        serializer.instance = pipeline
+
+        with patch(MUTABLE_WORKFLOWS_PATH, return_value=Workflow.objects.none()):
+            with patch.object(
+                Workflow.objects, "filter", wraps=Workflow.objects.filter
+            ) as mocked_filter:
+                serializer.get_fields()
+
+        mocked_filter.assert_called_once_with(pk=pipeline.workflow_id)