copy.deepcopy()

当对一个字典或者数组进行操作时

        l_project_member_delete=[]
        new_project_member_list=copy.deepcopy(all_data['project_member'])  #这里要用deepcopy

        if all_data['project_member']:
            if list_current_project_member: #原来和传入的都有
                for i in list_current_project_member:
                    if i in all_data['project_member']:
                        new_project_member_list.remove(i)  # 已存在的 从l中删除  #否则 删除new_project_member_list的同时也会删除 all_data[""]
                    else:　　　　　　　　　　　　　　　　　　　　　　中的内容
                        l_project_member_delete.append(i)  # 如果i 不再l中 说明，被删除了
        if not all_data['project_member']:
            if list_current_project_member:  # 原来和传入的都有
                l_project_member_delete=list_current_project_member