[Update] 优化user group serializer

apps/users/serializers/group.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 #
 from django.utils.translation import ugettext_lazy as _
-
+from django.db.models import Prefetch
 from rest_framework import serializers
 
 from common.serializers import AdaptedBulkListSerializer
@@ -18,15 +18,18 @@ __all__ = [
 class UserGroupSerializer(BulkOrgResourceModelSerializer):
     users = serializers.PrimaryKeyRelatedField(
         required=False, many=True, queryset=User.objects, label=_('User'),
-        # write_only=True, group can return many to many on detail
+        # write_only=True, # group can return many to many on detail
     )
 
     class Meta:
         model = UserGroup
         list_serializer_class = AdaptedBulkListSerializer
-        fields = [
-            'id', 'name',  'users', 'users_amount', 'comment',
-            'date_created', 'created_by',
+        fields_mini = ['id', 'name']
+        fields_small = fields_mini + [
+            'comment', 'date_created', 'created_by'
+        ]
+        fields = fields_mini + fields_small + [
+            'users', 'users_amount',
         ]
         extra_kwargs = {
             'created_by': {'label': _('Created by'), 'read_only': True}
@@ -50,5 +53,7 @@ class UserGroupSerializer(BulkOrgResourceModelSerializer):
     @classmethod
     def setup_eager_loading(cls, queryset):
         """ Perform necessary eager loading of data. """
-        queryset = queryset.annotate(users_amount=Count('users'))
+        queryset = queryset.prefetch_related(
+            Prefetch('users', queryset=User.objects.only('id'))
+        ).annotate(users_amount=Count('users'))
         return queryset