如何在某处获取或存盘 EmployeeSerializer 的资料，以便我可以再次使用它来获取活动成员的数量，而不是进行新的数据库呼叫来获取活动成员的数量？

class ProjectSerailizer(serializers.ModelSerializer):
  members = EmployeeSerializer(many=True)#returns all members of a project
  active_members_count = serializers.SerializerMethodField()# get count of members which are having status active
  class Meta:
    model = Project
    fields = ('id','name','members','active_members_count')
  
  def get_active_members_count(self,obj):
    #How can I omit this extra db call? as i am already having data in members variable from EmployeeSerializer, can i loop over members variable somehow and count the active ones?
    count = obj.members.filter(status='Active').count()
    return count

uj5u.com热心网友回复：

您可以在视图中使用select_related()和过滤设定查询集annotate()

django.db.models import Count, Q

queryset = Project.objects.select_related('members').annotate(
    active_members_count = Count('members', filter=Q(members__status = 'Active'))
)

然后您将获得active_members_count和其他members栏位ProjectSerailizer而无需额外的数据库呼叫