django的 信号详解编程语言

1、信号，其实就是钩子，可以在上面几种情况下定义执行某个函数，我们一般在project的__init__文件中定义，下面就是一个例子

2、用到模块需要导入，分别在下面的几个路径中

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 

from django.db.models.signals import post_init 


from django.db.models.signals import pre_save 

from django.db.models.signals import post_save 


from django.db.models.signals import pre_delete 

from django.db.models.signals import post_delete 

from django.db.models.signals import m2m_changed 

from django.db.models.signals import pre_migrate 

from django.db.models.signals import post_migrate 

from django.test.signals import setting_changed 

from django.test.signals import template_rendered 

from django.db.backends.signals import connection_created 

3、下面就是一个使用的例子，把函数注册到信号中

# 1、定义执行的函数 

def callback1(sender,**kwargs): 

 print("before pre_migrate") 

 print(sender,kwargs) 


Operations to perform: 

 Apply all migrations: admin, app1, auth, contenttypes, sessions 

before pre_migrate 

 AdminConfig: admin {signal: django.dispatch.dispatcher.Signal object at 0x01C755D0 , app_config: AdminConfig: admin , verbosity: 1, interactive: True, using: default, apps: django.db.migrations 

.state.StateApps object at 0x02CF1130 , plan: []} 

before pre_migrate 

 AuthConfig: auth {signal: django.dispatch.dispatcher.Signal object at 0x01C755D0 , app_config: AuthConfig: auth , verbosity: 1, interactive: True, using: default, apps: django.db.migrations.sta 

te.StateApps object at 0x02CF1130 , plan: []} 

before pre_migrate 

 ContentTypesConfig: contenttypes {signal: django.dispatch.dispatcher.Signal object at 0x01C755D0 , app_config: ContentTypesConfig: contenttypes , verbosity: 1, interactive: True, using: default,  

apps: django.db.migrations.state.StateApps object at 0x02CF1130 , plan: []} 

before pre_migrate 

 SessionsConfig: sessions {signal: django.dispatch.dispatcher.Signal object at 0x01C755D0 , app_config: SessionsConfig: sessions , verbosity: 1, interactive: True, using: default, apps: django.d 

b.migrations.state.StateApps object at 0x02CF1130 , plan: []} 

before pre_migrate 

 App1Config: app1 {signal: django.dispatch.dispatcher.Signal object at 0x01C755D0 , app_config: App1Config: app1 , verbosity: 1, interactive: True, using: default, apps: django.db.migrations.sta 

te.StateApps object at 0x02CF1130 , plan: []} 

Running migrations: 

 No migrations to apply. 

after pre_migrate 

 AdminConfig: admin {signal: django.dispatch.dispatcher.Signal object at 0x01C75610 , app_config: AdminConfig: admin , verbosity: 1, interactive: True, using: default, apps: django.db.migrations 

.state.StateApps object at 0x03183FD0 , plan: []} 

after pre_migrate 

 AuthConfig: auth {signal: django.dispatch.dispatcher.Signal object at 0x01C75610 , app_config: AuthConfig: auth , verbosity: 1, interactive: True, using: default, apps: django.db.migrations.sta 

te.StateApps object at 0x03183FD0 , plan: []} 

after pre_migrate 

 ContentTypesConfig: contenttypes {signal: django.dispatch.dispatcher.Signal object at 0x01C75610 , app_config: ContentTypesConfig: contenttypes , verbosity: 1, interactive: True, using: default,  

apps: django.db.migrations.state.StateApps object at 0x03183FD0 , plan: []} 

after pre_migrate 

 SessionsConfig: sessions {signal: django.dispatch.dispatcher.Signal object at 0x01C75610 , app_config: SessionsConfig: sessions , verbosity: 1, interactive: True, using: default, apps: django.d 

b.migrations.state.StateApps object at 0x03183FD0 , plan: []} 

after pre_migrate 

 App1Config: app1 {signal: django.dispatch.dispatcher.Signal object at 0x01C75610 , app_config: App1Config: app1 , verbosity: 1, interactive: True, using: default, apps: django.db.migrations.sta 

te.StateApps object at 0x03183FD0 , plan: []} 

E:/python/django_last 

上面是python给我们定义的信号，我们还可以自定义信号，下面说一下如何自定义信号，也是写在projec的__init__文件中

1、注册我们的信号，和信号的里的函数

# 1、导入模块 

import django.dispatch 


 # 导入自定义的信号,这里需要注意，导入__init__下的信号，直接用下面的方式就可以了 

 from django_last import test 

 # 触发信号，这里要记得要传参数,sender的意思是 谁发送的信号 

 test.send(sender="自定义信号",aa="django",bb="python") 

 return HttpResponse("自定义信号") 

3、效果如下

 无论是django定义的信号，还是我们自定义的信号，我们就可以为一个信号注册多个函数，这些多个函数会按照注册的顺序执行

原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/20811.html