⚡️(backend) optimize number of queries on document list view

I realized most of the database queries made when getting a document
list view were to include nested accesses. This detailed information
about accesses in only necessary for the document detail view.

I introduced a specific serializer for the document list view with
less fields. For a list of 20 documents with 5 accesses, we go down
from 3x5x20= 300 queries to just 3 queries.

src/backend/core/api/serializers.py

@@ -137,32 +137,55 @@ class BaseResourceSerializer(serializers.ModelSerializer):
         return {}
 
 
-class DocumentSerializer(BaseResourceSerializer):
-    """Serialize documents."""
+class ListDocumentSerializer(BaseResourceSerializer):
+    """Serialize documents with limited fields for display in lists."""
 
-    content = serializers.CharField(required=False)
-    accesses = DocumentAccessSerializer(many=True, read_only=True)
 
     class Meta:
         model = models.Document
         fields = [
             "id",
-            "content",
-            "title",
-            "accesses",
             "abilities",
+            "content",
+            "created_at",
             "link_role",
             "link_reach",
-            "created_at",
+            "title",
             "updated_at",
         ]
         read_only_fields = [
             "id",
-            "accesses",
             "abilities",
+            "created_at",
             "link_role",
             "link_reach",
+            "updated_at",
+        ]
+
+
+class DocumentSerializer(ListDocumentSerializer):
+    """Serialize documents with all fields for display in detail views."""
+
+    content = serializers.CharField(required=False)
+
+    class Meta:
+        model = models.Document
+        fields = [
+            "id",
+            "abilities",
+            "content",
             "created_at",
+            "link_role",
+            "link_reach",
+            "title",
+            "updated_at",
+        ]
+        read_only_fields = [
+            "id",
+            "abilities",
+            "created_at",
+            "link_role",
+            "link_reach",
             "updated_at",
         ]
 

src/backend/core/api/viewsets.py

@@ -346,15 +346,23 @@ class DocumentViewSet(
 ):
     """Document ViewSet"""
 
+    access_model_class = models.DocumentAccess
+    metadata_class = DocumentMetadata
+    ordering = ["-updated_at"]
     permission_classes = [
         permissions.AccessPermission,
     ]
-    serializer_class = serializers.DocumentSerializer
-    access_model_class = models.DocumentAccess
-    resource_field_name = "document"
     queryset = models.Document.objects.all()
-    ordering = ["-updated_at"]
-    metadata_class = DocumentMetadata
+    resource_field_name = "document"
+    serializer_class = serializers.DocumentSerializer
+
+    def get_serializer_class(self):
+        """
+        Use ListDocumentSerializer for list actions, otherwise use DocumentSerializer.
+        """
+        if self.action == "list":
+            return serializers.ListDocumentSerializer
+        return self.serializer_class
 
     def list(self, request, *args, **kwargs):
         """Restrict resources returned by the list endpoint"""