Django信号发射一次,收到两次 - 为什么？

Question

我正在使用Django信号,但它们似乎被接收了两次,即使发出一次.这是我正在使用的代码(它是一个使用上传与Django的简单包装器)...

# Signal-emitting code... emits whenever a file upload is received
# ----------------------------------------------------------------
upload_recieved = django.dispatch.Signal(providing_args=['data'])

def upload(request, *args, **kwargs):
    if request.method == 'POST':
        if request.FILES:
            print 'sending signal'
            upload_recieved.send(sender='uploadify', data=request.FILES['Filedata'])
    return HttpResponse('True')

# Signal-receiving code...
# ----------------------------------------------------------------    
def upload_received_handler(sender, data, **kwargs):
    print 'upload received handler'

print 'connecting signal'
upload_recieved.connect(upload_received_handler)

(我刚注意到我的信号拼错了)

我确定你注意到那里的印刷声明.在控制台上,这是它显示的内容:

(server starts)
connecting signal

...

sending signal
upload received handler
upload received handler     # << == where is this 2nd one coming from?
127.0.0.1 - - [25/Sep/2009 07:28:22] "POST /uploadify/upload/ HTTP/1.1" 200 -

(也奇怪的是,为什么Django会在信号被触发后报告页面POST？)

Answer 1

这在我之前发生过,这是由于您连接两次输入信号的模块.要确保信号未连接两次,您可以设置dispatch_uid:

upload_recieved.connect(upload_received_handler, dispatch_uid="some.unique.string.id")

更新 它实际上在这里记录:http://code.djangoproject.com/wiki/Signals#Helppost_saveseemstobeemittedtwiceforeachsave