Addons: improve serializer performance (#12335)

- Instead of passing the version slug to the project serializer, just
pass the actual version, so we can use resolve_version, this reduces one
less query.
- We were passing the resolver around some places, but doing this weird
thing where removing it from kwargs, and then adding it again. This
introduced a bug that was creating a new resolver for each serializer
instance instead of re-using the one passed to the initializer.

This took ~10ms off locally

<img width="1550" height="237" alt="Screenshot 2025-07-17 at 16-04-42
Silky - Profiling -"
src="https://github.com/user-attachments/assets/5667e02c-fe74-4583-b2db-43a086c994b5"
/>

Note: I'm running these benchmarks in power saver mode, otherwise my
computer is too fast and can't get meaningful comparisons :D

Author: stsewd

readthedocs/api/v3/serializers.py

@@ -355,16 +355,11 @@ class Meta:
             "privacy_level",
         ]
 
-    def __init__(self, *args, resolver=None, version_serializer=None, **kwargs):
-        super().__init__(*args, **kwargs)
-
+    def __init__(self, *args, resolver=None, **kwargs):
         # Use a shared resolver to reduce the amount of DB queries while
         # resolving version URLs.
-        self.resolver = kwargs.pop("resolver", Resolver())
-
-        # Allow passing a specific serializer when initializing it.
-        # This is required to pass ``VersionSerializerNoLinks`` from the addons API.
-        self.version_serializer = version_serializer or VersionSerializer
+        self.resolver = resolver or Resolver()
+        super().__init__(*args, **kwargs)
 
     def get_downloads(self, obj):
         downloads = obj.get_downloads()
@@ -387,7 +382,8 @@ def get_aliases(self, obj):
             if obj.slug == LATEST:
                 alias_version = obj.project.get_original_latest_version()
             if alias_version and alias_version.active:
-                return [self.version_serializer(alias_version).data]
+                # NOTE: we use __class__, as this serializer can be subclassed.
+                return [self.__class__(alias_version).data]
         return []
 
 
@@ -472,9 +468,9 @@ def get_downloads(self, obj):
         return None
 
     def get_documentation(self, obj):
-        version_slug = getattr(self.parent, "version_slug", None)
+        version = getattr(self.parent, "version", None)
         resolver = getattr(self.parent, "resolver", Resolver())
-        return obj.get_docs_url(version_slug=version_slug, resolver=resolver)
+        return resolver.resolve_version(project=obj, version=version)
 
 
 class RepositorySerializer(serializers.Serializer):
@@ -837,13 +833,13 @@ class Meta:
             ),
         }
 
-    def __init__(self, *args, **kwargs):
-        # Receive a `Version.slug` here to build URLs properly
-        self.version_slug = kwargs.pop("version_slug", None)
+    def __init__(self, *args, resolver=None, **kwargs):
+        # Receive a `Version` here to build URLs properly
+        self.version = kwargs.pop("version", None)
 
         # Use a shared resolver to reduce the amount of DB queries while
         # resolving version URLs.
-        self.resolver = kwargs.pop("resolver", Resolver())
+        self.resolver = resolver or Resolver()
 
         super().__init__(*args, **kwargs)
         # When using organizations, projects don't have the concept of users.

readthedocs/proxito/tests/test_hosting.py

@@ -785,7 +785,7 @@ def test_number_of_queries_project_version_slug(self):
                 active=True,
             )
 
-        with self.assertNumQueries(20):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -814,7 +814,7 @@ def test_number_of_queries_url(self):
                 active=True,
             )
 
-        with self.assertNumQueries(22):
+        with self.assertNumQueries(18):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -850,7 +850,7 @@ def test_number_of_queries_url_subproject(self):
                 active=True,
             )
 
-        with self.assertNumQueries(26):
+        with self.assertNumQueries(22):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -866,7 +866,7 @@ def test_number_of_queries_url_subproject(self):
         assert r.status_code == 200
 
         # Test parent project has fewer queries
-        with self.assertNumQueries(21):
+        with self.assertNumQueries(17):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -892,7 +892,7 @@ def test_number_of_queries_url_translations(self):
                 language=language,
             )
 
-        with self.assertNumQueries(39):
+        with self.assertNumQueries(35):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {
@@ -1042,7 +1042,7 @@ def test_file_tree_diff(self, get_manifest):
                 ],
             ),
         ]
-        with self.assertNumQueries(27):
+        with self.assertNumQueries(25):
             r = self.client.get(
                 reverse("proxito_readthedocs_docs_addons"),
                 {

readthedocs/proxito/views/hosting.py

@@ -252,24 +252,9 @@ class RelatedProjectSerializerNoLinks(NoLinksMixin, RelatedProjectSerializer):
 class ProjectSerializerNoLinks(NoLinksMixin, ProjectSerializer):
     related_project_serializer = RelatedProjectSerializerNoLinks
 
-    def __init__(self, *args, **kwargs):
-        resolver = kwargs.pop("resolver", Resolver())
-        super().__init__(
-            *args,
-            resolver=resolver,
-            **kwargs,
-        )
-
 
 class VersionSerializerNoLinks(NoLinksMixin, VersionSerializer):
-    def __init__(self, *args, **kwargs):
-        resolver = kwargs.pop("resolver", Resolver())
-        super().__init__(
-            *args,
-            resolver=resolver,
-            version_serializer=VersionSerializerNoLinks,
-            **kwargs,
-        )
+    pass
 
 
 class BuildSerializerNoLinks(NoLinksMixin, BuildSerializer):
@@ -616,7 +601,7 @@ def _get_projects_response(self, *, request, project, version, resolver):
             translations = ProjectSerializerNoLinks(
                 translations_qs,
                 resolver=resolver,
-                version_slug=version.slug if version else None,
+                version=version,
                 many=True,
             ).data
         else:
@@ -626,7 +611,7 @@ def _get_projects_response(self, *, request, project, version, resolver):
             "current": ProjectSerializerNoLinks(
                 project,
                 resolver=resolver,
-                version_slug=version.slug if version else None,
+                version=version,
             ).data,
             "translations": translations,
         }