Don't use .save() in validate_version_metadata

dandiapi/api/services/metadata/__init__.py

@@ -129,36 +129,33 @@ def _build_validatable_version_metadata(version: Version) -> dict:
     with transaction.atomic():
         # validating version metadata needs to lock the version to avoid racing with
         # other modifications e.g. aggregate_assets_summary.
-        version = (
-            Version.objects.filter(id=version.id, status=Version.Status.PENDING)
-            .select_for_update()
-            .first()
-        )
-        version.status = Version.Status.VALIDATING
-        version.save()
+        version_qs = Version.objects.filter(id=version.id).select_for_update()
+        if not version_qs.filter(status=Version.Status.PENDING).exists():
+            # TODO: Should raise an error here?
+            return
 
+        # Set to validating and continue
+        version_qs.update(status=Version.Status.VALIDATING)
         try:
             validate(
-                _build_validatable_version_metadata(version),
+                _build_validatable_version_metadata(version_qs.first()),
                 schema_key='PublishedDandiset',
                 json_validation=True,
             )
         except dandischema.exceptions.ValidationError as e:
             logger.info('Error while validating version %s', version.id)
-            version.status = Version.Status.INVALID
-
-            validation_errors = _collect_validation_errors(e)
-            version.validation_errors = validation_errors
-            version.save()
+            version_qs.update(
+                status=Version.Status.INVALID, validation_errors=_collect_validation_errors(e)
+            )
             return
         except ValueError as e:
             # A bare ValueError is thrown when dandischema generates its own exceptions, like a
             # mismatched schemaVersion.
-            version.status = Version.Status.INVALID
-            version.validation_errors = [{'field': '', 'message': str(e)}]
-            version.save()
+            logger.info('Error while validating version %s', version.id)
+            version_qs.update(
+                status=Version.Status.INVALID, validation_errors=[{'field': '', 'message': str(e)}]
+            )
             return
+
         logger.info('Successfully validated version %s', version.id)
-        version.status = Version.Status.VALID
-        version.validation_errors = []
-        version.save()
+        version_qs.update(status=Version.Status.VALID, validation_errors=[])

dandiapi/api/tests/test_tasks.py

@@ -4,6 +4,7 @@
 from django.conf import settings
 from django.contrib.auth.models import User
 from django.core.files.storage import Storage
+from django.forms.models import model_to_dict
 from guardian.shortcuts import assign_perm
 import pytest
 from rest_framework.test import APIClient
@@ -193,6 +194,28 @@ def test_validate_version_metadata(draft_version: Version, asset: Asset):
     assert draft_version.validation_errors == []
 
 
+@pytest.mark.django_db()
+def test_validate_version_metadata_no_side_effects(draft_version: Version, asset: Asset):
+    draft_version.assets.add(asset)
+
+    # Set the version `status` and `validation_errors` fields to something
+    # which can't be a result of validate_version_metadata
+    draft_version.status = Version.Status.PENDING
+    draft_version.validation_errors = [{'foo': 'bar'}]
+    draft_version.save()
+
+    # Validate version metadata, storing the model data before and after
+    old_data = model_to_dict(draft_version)
+    tasks.validate_version_metadata_task(draft_version.id)
+    draft_version.refresh_from_db()
+    new_data = model_to_dict(draft_version)
+
+    # Check that change is isolated to these two fields
+    assert old_data.pop('status') != new_data.pop('status')
+    assert old_data.pop('validation_errors') != new_data.pop('validation_errors')
+    assert old_data == new_data
+
+
 @pytest.mark.django_db()
 def test_validate_version_metadata_malformed_schema_version(draft_version: Version, asset: Asset):
     draft_version.assets.add(asset)