Django信号

    from django.core.signals import request_finished   #请求结束后，自动触发
    from django.core.signals import request_started  # 请求到来前，自动触发
    from django.core.signals import got_request_exception # 请求异常后，自动触发

    from django.db.models.signals import class_prepared # 程序启动时，检测已注册的app中modal类，对于每一个类，自动触发
    from django.db.models.signals import pre_init, post_init
    #pre_init          # django的model执行其构造方法前，自动触发
    #post_init         # django的model执行其构造方法后，自动触发

    from django.db.models.signals import pre_save, post_save
    # pre_save     # django的model对象保存前，自动触发
    #post_save     # django的model对象保存后，自动触发
   
    from django.db.models.signals import pre_delete, post_delete
    #pre_delete      django的model对象删除前，自动触发
    #post_delete     django的model对象删除后，自动触发
    from django.db.models.signals import m2m_changed
    # django的model中使用m2m字段操作第三张表（add,remove,clear）前后，自动触发
    from django.db.models.signals import pre_migrate, post_migrate
    # pre_migrate        # 执行migrate命令前，自动触发
    # post_migrate         # 执行migrate命令后，自动触发
    from django.test.signals import setting_changed
        # 使用test测试修改配置文件时，自动触发
    from django.test.signals import template_rendered
        # 使用test测试渲染模板时，自动触发    
    from django.db.backends.signals import connection_created
        # 创建数据库连接时，自动触发

from django.db.models.signals import pre_save, post_save

def callback(sender, **kwargs):
    print("xxoo_callback")
    print(sender, kwargs)    #sender<class‘django.core.handlers.wsgi.WSGIHandler‘>  固定参数
post_save.connect(callback)

from django.dispatch import receiver
@receiver(post_save)
def callback1(sender, **kwargs):
    print("xxoo_callback1111111")
    print(sender, kwargs)