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Django里面还提供了一个功能叫做信号。信号类似触发器,可以指定在某个事件发生前后自动执行对应的函数。
Django自带了一些信号,如下所示:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | Model signals pre_init # django的modal执行其构造方法前,自动触发 post_init # django的modal执行其构造方法后,自动触发 pre_save # django的modal对象保存前,自动触发 post_save # django的modal对象保存后,自动触发 pre_delete # django的modal对象删除前,自动触发 post_delete # django的modal对象删除后,自动触发 m2m_changed # django的modal中使用m2m字段操作第三张表(add,remove,clear)前后,自动触发 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 Management signals pre_migrate # 执行migrate命令前,自动触发 post_migrate # 执行migrate命令后,自动触发 Request / response signals request_started # 请求到来前,自动触发 request_finished # 请求结束后,自动触发 got_request_exception # 请求异常后,自动触发 Test signals setting_changed # 使用test测试修改配置文件时,自动触发 template_rendered # 使用test测试渲染模板时,自动触发 Database Wrappers connection_created # 创建数据库连接时,自动触发 |
如果需要使用的话,只需要导入对应的类,然后自己创建一个函数,再把自己的函数绑定到对应的信号就会自动执行了(这个过程叫做注册信号)。
例1:
创建一个sg.py,可以看见注册信号有2种方式写都是可以的,f1和f2用的第一种;f3用的第二种
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | from django.core.signals import request_finished from django.core.signals import request_started from django.core.signals import got_request_exception from django.db.models.signals import class_prepared from django.db.models.signals import pre_init, post_init from django.db.models.signals import pre_save, post_save from django.db.models.signals import pre_delete, post_delete from django.db.models.signals import m2m_changed from django.db.models.signals import pre_migrate, post_migrate from django.test.signals import setting_changed from django.test.signals import template_rendered from django.db.backends.signals import connection_created def f1(sender, * * kwargs): print ( "xxoo_callback" ) # print(sender,kwargs) def f2(sender, * * kwargs): print ( "Do something before request" ) print ( "--------------------------" ) #注册信号方法1 pre_save.connect(f1) request_started.connect(f2) #注册信号方法2 from django.dispatch import receiver @receiver (request_finished) def f3(sender, * * kwargs): print ( "--------------------------" ) print ( "Do something after request" ) #自定义一个信号叫做pizza_done,要求提供两个参数 import django.dispatch pizza_done = django.dispatch.Signal(providing_args = [ "toppings" , "size" ]) #下面步骤一样的,注册信号,绑定回调函数 def callback(sender, * * kwargs): print ( "callback" ) print (sender,kwargs) pizza_done.connect(callback) |
我把他直接导入到_init_.py里面这样运行的时候自动执行
Views.py
自己写的一个视图函数
1 2 3 4 5 6 7 8 9 10 | def signal(reuqest): from app01 import models obj = models.UserInf(user = 'root' ) obj.save() obj = models.UserInf(user = 'root' ) obj.save() obj = models.UserInf(user = 'root' ) obj.save() from sg import pizza_done pizza_done.send(sender = "asdfasdf" ,toppings = 123 , size = 456 ) |
执行结果,在获取request之前,触发了f2,然后每次保存数据都触发了f1,然后通过send触发了一个自定义的信号,完成request之后,触发了f3
1 2 3 4 5 6 7 8 9 10 | Do something before request - - - - - - - - - - - - - - - - - - - - - - - - - - xxoo_callback xxoo_callback xxoo_callback callback asdfasdf { 'signal' : <django.dispatch.dispatcher.Signal object at 0x03342FF0 >, 'toppings' : 123 , 'size' : 456 } [ 07 / Sep / 2017 16 : 29 : 16 ] "GET /signal/ HTTP/1.1" 200 2 - - - - - - - - - - - - - - - - - - - - - - - - - - Do something after request |