知识点
- 概念
- 如何监听信号
- Django内置信号
- 自定义信号
- 使用Django内置信号
概念
Django 提供一个“信号分发器”，允许解耦的应用在框架的其它地方发生操作时会被通知到。
也就是说在特定事件发生时，可以发送一个信号去通知注册了这个信号的一个或者多个回调，在回调里进行逻辑处理。
如何监听信号
拥有一个Signal实例
信号回调
将信号回调绑定到Signal实例
在特定事件中Signal发送信号
Django内置信号
django.db.models.signals.pre_save & post_save�在模型 save()方法调用之前或之后发送。
django.db.models.signals.pre_delete & post_delete�在模型delete()方法或查询集的delete() 方法调用之前或之后发送。
django.core.signals.request_started & request_finished�Django建立或关闭HTTP 请求时发送。
参考文档
实验操作
自定义信号
注册信号
【signal.py】
from django.dispatch import Signal, receiver
signalAllen = Signal(providing_args=['allen'])
@receiver(signalAllen)
def signal_callback(sender, **kwargs):
print(sender, kwargs)
print('signal_callback called')
# 注册，或者使用装饰器注册
# signalAllen.connect(signal_callback)
# 可以定义多个
@receiver(signalAllen)
def signal_callback1(sender, **kwargs):
print(sender, kwargs)
print('signal_callback1 called')
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^$', view=views.index),
]
【views.py】
from . import signals
# Create your views here.
def index(request):
signals.signalAllen.send(sender=None, allen='test')
return render(request, template_name='index.html')
删除信号
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^disconnect/$', view=views.disconnect_signal),
]
【views.py】
def disconnect_signal(request):
signals.signalAllen.disconnect(signals.signal_callback)
return render(request, template_name='index.html')
Django 内置信号
简单使用
【views.py】
from django.shortcuts import render
from .models import Poem, Task
# Create your views here.
def modify(request):
poem = Poem.objects.get(pk=1)
poem.title = '1'
# 会发送两个信号pre_save和post_save
poem.save()
task = Task.objects.get(pk=1)
task.name = '1'
task.save()
return render(request, template_name='index.html')
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^modify/$', view=views.modify),
]
【singals.py】
from django.db.models.signals import pre_save, post_save
@receiver(pre_save)
def pre_save_callback(sender, **kwargs):
print('pre_save_callback')
@receiver(post_save)
def post_save_callback(sender, **kwargs):
print('post_save_callback')
指定信号
【views.py】
from django.shortcuts import render
from .models import Poem, Task
# Create your views here.
def modify(request):
poem = Poem.objects.get(pk=1)
poem.title = '1'
# 会发送两个信号pre_save和post_save
poem.save()
task = Task.objects.get(pk=1)
task.name = '1'
task.save()
return render(request, template_name='index.html')
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^modify/$', view=views.modify),
]
【singals.py】
from django.db.models.signals import pre_save, post_save
from .models import Poem, Task
@receiver(pre_save, sender=Poem)
def pre_save_callback(sender, **kwargs):
print('pre_save_callback', sender, kwargs)
@receiver(post_save, sender=Task)
def post_save_callback(sender, **kwargs):
print('post_save_callback', sender, kwargs)
