知識點
- 概念
- 如何監(jiān)聽信號
- Django內(nèi)置信號
- 自定義信號
- 使用Django內(nèi)置信號
概念
Django 提供一個“信號分發(fā)器”心软，允許解耦的應用在框架的其它地方發(fā)生操作時會被通知到。
也就是說在特定事件發(fā)生時著蛙，可以發(fā)送一個信號去通知注冊了這個信號的一個或者多個回調(diào)删铃，在回調(diào)里進行邏輯處理。
如何監(jiān)聽信號
擁有一個Signal實例
信號回調(diào)
將信號回調(diào)綁定到Signal實例
在特定事件中Signal發(fā)送信號
Django內(nèi)置信號
django.db.models.signals.pre_save & post_save?在模型 save()方法調(diào)用之前或之后發(fā)送踏堡。
django.db.models.signals.pre_delete & post_delete?在模型delete()方法或查詢集的delete() 方法調(diào)用之前或之后發(fā)送猎唁。
django.core.signals.request_started & request_finished?Django建立或關(guān)閉HTTP 請求時發(fā)送。
參考文檔
實驗操作
自定義信號
注冊信號
【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')
# 注冊顷蟆，或者使用裝飾器注冊
# signalAllen.connect(signal_callback)
# 可以定義多個
@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'^$', view=views.index),
]
【views.py】
from . import signals
# Create your views here.
def index(request):
signals.signalAllen.send(sender=None, allen='test')
return render(request, template_name='index.html')
刪除信號
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^disconnect/$', view=views.disconnect_signal),
]
【views.py】
def disconnect_signal(request):
signals.signalAllen.disconnect(signals.signal_callback)
return render(request, template_name='index.html')
Django 內(nèi)置信號
簡單使用
【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'
# 會發(fā)送兩個信號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/$', view=views.modify),
]
【singals.py】
from django.db.models.signals import pre_save, post_save
@receiver(pre_save)
def pre_save_callback(sender, **kwargs):
print('pre_save_callback')
@receiver(post_save)
def post_save_callback(sender, **kwargs):
print('post_save_callback')
指定信號
【views.py】
from django.shortcuts import render
from .models import Poem, Task
# Create your views here.
def modify(request):
poem = Poem.objects.get(pk=1)
poem.title = '1'
# 會發(fā)送兩個信號pre_save和post_save
poem.save()
task = Task.objects.get(pk=1)
task.name = '1'
task.save()
return render(request, template_name='index.html')
【urls.py】
from django.conf.urls import url
from . import views
urlpatterns = [
url(r'^modify/$', 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)
