Attempt to reduce the number of database calls for user_api serialization

openedx/core/djangoapps/user_api/serializers.py

@@ -22,12 +22,7 @@ class UserSerializer(serializers.HyperlinkedModelSerializer):
         """
         Return the name attribute from the user profile object if profile exists else none
         """
-        try:
-            profile = UserProfile.objects.get(user=user)
-        except UserProfile.DoesNotExist:
-            return None
-
-        return profile.name
+        return user.profile.name
 
     def get_preferences(self, user):
         """

openedx/core/djangoapps/user_api/views.py

@@ -956,7 +956,7 @@ class UserViewSet(viewsets.ReadOnlyModelViewSet):
     """
     authentication_classes = (authentication.SessionAuthentication,)
     permission_classes = (ApiKeyHeaderPermission,)
-    queryset = User.objects.all().prefetch_related("preferences")
+    queryset = User.objects.all().prefetch_related("preferences").select_related("profile")
     serializer_class = UserSerializer
     paginate_by = 10
     paginate_by_param = "page_size"
@@ -982,7 +982,7 @@ class ForumRoleUsersListView(generics.ListAPIView):
             raise ParseError('course_id must be specified')
         course_id = SlashSeparatedCourseKey.from_deprecated_string(course_id_string)
         role = Role.objects.get_or_create(course_id=course_id, name=name)[0]
-        users = role.users.all()
+        users = role.users.prefetch_related("preferences").select_related("profile").all()
         return users
 
 
@@ -1011,7 +1011,7 @@ class PreferenceUsersListView(generics.ListAPIView):
     paginate_by_param = "page_size"
 
     def get_queryset(self):
-        return User.objects.filter(preferences__key=self.kwargs["pref_key"]).prefetch_related("preferences")
+        return User.objects.filter(preferences__key=self.kwargs["pref_key"]).prefetch_related("preferences").select_related("profile")
 
 
 class UpdateEmailOptInPreference(APIView):