Avoid reloading the zone after creating an element

arkindex/documents/serializers/elements.py

@@ -365,14 +365,19 @@ class ElementCreateSerializer(ElementLightSerializer):
             # - use .only('id') to load only the id
             #   This works because of the unique constraint on image_id + polygon
             try:
-                zone_id = Zone.objects.filter(
+                zone = Zone.objects.filter(
                     image_id=image.id,
                     polygon=polygon
-                ).only('id').get().id
+                ).only('id').get()
             except Zone.DoesNotExist:
-                zone_id = image.zones.create(polygon=polygon).id
+                zone = image.zones.create(polygon=polygon)
+
+            # Set the zone attributes to avoid retrieving the zone, image and server again
+            # when the endpoint returns the created element without the slim_output mode.
+            zone.image = image
+            zone.polygon = polygon
         else:
-            zone_id = None
+            zone = None
 
         element = Element.objects.create(
             corpus=validated_data['corpus'],
@@ -380,7 +385,7 @@ class ElementCreateSerializer(ElementLightSerializer):
             name=validated_data['name'],
             source=validated_data.get('source'),
             worker_version=validated_data.get('worker_version'),
-            zone_id=zone_id,
+            zone=zone,
         )
 
         # Make relation to parent, without dealing with children as there cannot be

arkindex/documents/tests/test_create_elements.py

@@ -91,7 +91,7 @@ class TestCreateElements(FixtureAPITestCase):
             name='The castle of my dreams',
             image=str(self.image.id),
         )
-        with self.assertNumQueries(19):
+        with self.assertNumQueries(16):
             response = self.client.post(**request)
         self.assertEqual(response.status_code, status.HTTP_201_CREATED)
         data = response.json()
@@ -230,7 +230,7 @@ class TestCreateElements(FixtureAPITestCase):
             image=str(self.image.id),
             polygon=polygon
         )
-        with self.assertNumQueries(19):
+        with self.assertNumQueries(16):
             response = self.client.post(**request)
         self.assertEqual(response.status_code, status.HTTP_201_CREATED)
         data = response.json()