Use select_related to avoid an extra query when creating an element

arkindex/documents/serializers/elements.py

@@ -294,7 +294,7 @@ class ElementCreateSerializer(ElementLightSerializer):
     type = serializers.SlugField(source='type.slug')
     corpus = serializers.PrimaryKeyRelatedField(queryset=Corpus.objects.none())
     image = serializers.PrimaryKeyRelatedField(
-        queryset=Image.objects.using('default').all().prefetch_related('server'),
+        queryset=Image.objects.using('default').all().select_related('server'),
         required=False,
         help_text='Link this element to an image by UUID via a polygon.',
     )

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(20):
+        with self.assertNumQueries(19):
             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(20):
+        with self.assertNumQueries(19):
             response = self.client.post(**request)
         self.assertEqual(response.status_code, status.HTTP_201_CREATED)
         data = response.json()
@@ -342,7 +342,7 @@ class TestCreateElements(FixtureAPITestCase):
         self.image.height = 0
         self.image.status = S3FileStatus.Unchecked
         self.image.save()
-        with self.assertNumQueries(7):
+        with self.assertNumQueries(6):
             response = self.client.post(**request)
         self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
         self.assertDictEqual(response.json(), {'image': ['This image does not have valid dimensions.']})
@@ -370,7 +370,7 @@ class TestCreateElements(FixtureAPITestCase):
             image=str(self.image.id),
         )
         request['path'] += '?slim_output=true'
-        with self.assertNumQueries(15):
+        with self.assertNumQueries(14):
             response = self.client.post(**request)
         self.assertEqual(response.status_code, status.HTTP_201_CREATED)
         element = self.corpus.elements.get(id=response.json()['id'])