django 信号介绍 1.11

Django中提供了“信号调度”，用于在框架执行操作时解耦。通俗来讲，就是一些动作发生的时候，信号允许特定的发送者去提醒一些接受者

1、Django内置信号

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

这个信号 django内部已经全部定死 已经埋下触发信号操作

于Django内置的信号，仅需注册指定信号，当程序执行相应操作时，自动触发注册函数：

要注册 先导入

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 callback(sender, **kwargs):
　　print("xxoo_callback")
　　print(sender,kwargs)

xxoo.connect(callback)
# xxoo指上述导入的内容

xxoo是什么 比如

.connect() 里面 传的 是一个自定义函数  代表在信号里面 注册一个函数

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("end")

pre_init.connect(f1)

也可以注册多个函数 按照顺序执行

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("end")

def f2(sender, **kwargs):
    print("end22")

pre_init.connect(f1)
pre_init.connect(f2)

想在django 应用 注册的函数的 信号注册到django

在django项目 创建一个sg.py 文件

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")

pre_init.connect(f1)

django执行 models构造方法前 自动触发信号

在django项目中的 __init__.py 文件 导入 sg.py 模块   那就django程序一运行，自动把sg.py 代码加载到内存，然后相应信号函数就注册了

urls.py signal函数

from django.conf.urls import url
from django.contrib import admin
from django.conf.urls import include
from app01 import views

urlpatterns = [
    # url(r‘^admin/‘, admin.site.urls),
    url(r‘^login/‘, views.login),
    url(r‘^index/‘, views.index),
    url(r‘^logout/‘, views.logout),
    url(r‘^test/‘, views.test),
    url(r‘^cache/‘, views.cache),
    url(r‘^signal/‘, views.signal),
]

views.py signal函数 用来测试注册的信号

def signal(request):

    from app01 import models

    obj = models.UserInfo(username=‘mike‘)
    print("end")
    obj.save()

    obj = models.UserInfo(username=‘mike‘)
    print("end1")
    obj.save()

    obj = models.UserInfo(username=‘mike‘)
    print("end2")
    obj.save()

    return HttpResponse("ok")

一启动django 注册的函数马上加载到内存了

xxoo
xxoo
System check identified no issues (0 silenced).
January 07, 2019 - 17:17:06
Django version 1.11, using settings ‘day21django.settings‘
Starting development server at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK

执行django signal url

后台拿到信息

每一次 执行 models构造方法前 自动触发信号 函数 然后打印信息

mike
jack
tom
小张
小刚
老张
xxoo
end
xxoo
end1
xxoo
end2
xiaogang
xiaoming
peter
[07/Jan/2019 17:25:01] "GET /signal/ HTTP/1.1" 200 2

原文地址：https://www.cnblogs.com/mingerlcm/p/10226906.html