Prefetch default included resources (#900)

Co-authored-by: Oliver Sauder <[email protected]>

Author: SafaAlfulaij

Diff for: CHANGELOG.md

@@ -25,6 +25,7 @@ any parts of the framework not mentioned in the documentation should generally b
       OrderViewSet.as_view({'get': 'retrieve_related'}),
       name='order-related'),
   ```
+* Ensure default `included_resources` are considered when calculating prefetches.
 
 
 ### Deprecated

Diff for: example/tests/test_performance.py

@@ -1,7 +1,7 @@
 from django.utils import timezone
 from rest_framework.test import APITestCase
 
-from example.factories import CommentFactory
+from example.factories import CommentFactory, EntryFactory
 from example.models import Author, Blog, Comment, Entry
 
 
@@ -36,6 +36,7 @@ def setUp(self):
         )
         self.comment = Comment.objects.create(entry=self.first_entry)
         CommentFactory.create_batch(50)
+        EntryFactory.create_batch(50)
 
     def test_query_count_no_includes(self):
         """We expect a simple list view to issue only two queries.
@@ -49,7 +50,7 @@ def test_query_count_no_includes(self):
             self.assertEqual(len(response.data["results"]), 25)
 
     def test_query_count_include_author(self):
-        """We expect a list view with an include have three queries:
+        """We expect a list view with an include have five queries:
 
         1. Primary resource COUNT query
         2. Primary resource SELECT
@@ -70,3 +71,16 @@ def test_query_select_related_entry(self):
         with self.assertNumQueries(2):
             response = self.client.get("/comments?include=writer&page[size]=25")
             self.assertEqual(len(response.data["results"]), 25)
+
+    def test_query_prefetch_uses_included_resources(self):
+        """We expect a list view with `included_resources` to have three queries:
+
+        1. Primary resource COUNT query
+        2. Primary resource SELECT
+        3. Comments prefetched
+        """
+        with self.assertNumQueries(3):
+            response = self.client.get(
+                "/entries?fields[entries]=comments&page[size]=25"
+            )
+            self.assertEqual(len(response.data["results"]), 25)

Diff for: rest_framework_json_api/serializers.py

@@ -137,7 +137,7 @@ def validate_path(serializer_class, field_path, path):
                 validate_path(this_included_serializer, new_included_field_path, path)
 
         if request and view:
-            included_resources = get_included_resources(request)
+            included_resources = get_included_resources(request, self)
             for included_field_name in included_resources:
                 included_field_path = included_field_name.split(".")
                 if "related_field" in view.kwargs:

Diff for: rest_framework_json_api/views.py

@@ -63,7 +63,9 @@ def get_prefetch_related(self, include):
     def get_queryset(self, *args, **kwargs):
         qs = super(PreloadIncludesMixin, self).get_queryset(*args, **kwargs)
 
-        included_resources = get_included_resources(self.request)
+        included_resources = get_included_resources(
+            self.request, self.get_serializer_class()
+        )
         for included in included_resources + ["__all__"]:
 
             select_related = self.get_select_related(included)
@@ -82,7 +84,9 @@ def get_queryset(self, *args, **kwargs):
         """ This mixin adds automatic prefetching for OneToOne and ManyToMany fields. """
         qs = super(AutoPrefetchMixin, self).get_queryset(*args, **kwargs)
 
-        included_resources = get_included_resources(self.request)
+        included_resources = get_included_resources(
+            self.request, self.get_serializer_class()
+        )
 
         for included in included_resources + ["__all__"]:
             # If include was not defined, trying to resolve it automatically