Prevent updating an element's zone to an invalid image

arkindex/documents/serializers/elements.py

@@ -251,7 +251,6 @@ class ElementSerializer(ElementSlimSerializer):
         return instance
 
     def update(self, instance, validated_data):
-
         image = validated_data.pop('image', None)
         polygon = validated_data.pop('polygon', None)
         if polygon or image:
@@ -263,6 +262,9 @@ class ElementSerializer(ElementSlimSerializer):
                     })
                 image = instance.zone.image
 
+            if image.width == 0 or image.height == 0:
+                raise ValidationError({'image': ['This image does not have valid dimensions.']})
+
             if not polygon:
                 if instance.zone:
                     polygon = instance.zone.polygon

arkindex/documents/tests/test_patch_elements.py

@@ -195,6 +195,27 @@ class TestPatchElements(FixtureAPITestCase):
         self.assertEqual(self.vol.zone.polygon.width, 20)
         self.assertEqual(self.vol.zone.polygon.height, 10)
 
+    def test_patch_element_invalid_dimensions(self):
+        self.client.force_login(self.user)
+        self.assertIsNone(self.vol.zone)
+        bad_image = self.imgsrv.images.create(
+            path='oh-no',
+            status=S3FileStatus.Unchecked,
+            width=0,
+            height=0,
+        )
+        response = self.client.patch(
+            reverse('api:element-retrieve', kwargs={'pk': str(self.vol.id)}),
+            data={
+                'image': str(bad_image.id),
+                'polygon': [[10, 20], [10, 30], [30, 30], [30, 20], [10, 20]],
+            },
+            format='json',
+        )
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertDictEqual(response.json(), {'image': ['This image does not have valid dimensions.']})
+        self.assertIsNone(self.vol.zone)
+
     def test_element_patch_type_allowed_transcription(self):
         """
         The base number of requests is increased by 1 because