Question

我需要使用模型进行保存，但我需要在保存之前断开信号的某些接收器。

我的意思是，

我有一个模特：

class MyModel(models.Model):
    ...

def pre_save_model(sender, instance, **kwargs):
    ...

pre_save.connect(pre_save_model, sender=MyModel)

并且在代码中的另一个地方我需要类似的东西：

a = MyModel()
...
disconnect_signals_for_model(a)
a.save()
...
reconnect_signals_for_model(a)

因为在这种情况下我需要保存模型而不执行函数pre_save_model。

Answer 1

对于干净且可重复使用的解决方案，您可以使用上下文管理器：

class temp_disconnect_signal():
    """ Temporarily disconnect a model from a signal """
    def __init__(self, signal, receiver, sender, dispatch_uid=None):
        self.signal = signal
        self.receiver = receiver
        self.sender = sender
        self.dispatch_uid = dispatch_uid

    def __enter__(self):
        self.signal.disconnect(
            receiver=self.receiver,
            sender=self.sender,
            dispatch_uid=self.dispatch_uid,
            weak=False
        )

    def __exit__(self, type, value, traceback):
        self.signal.connect(
            receiver=self.receiver,
            sender=self.sender,
            dispatch_uid=self.dispatch_uid,
            weak=False
        )

现在，您可以执行以下操作：

from django.db.models import signals

from your_app.signals import some_receiver_func
from your_app.models import SomeModel

...
kwargs = {
    'signal': signals.post_save,
    'receiver': some_receiver_func,
    'sender': SomeModel, 
    'dispatch_uid': "optional_uid"
}
with temp_disconnect_signal(**kwargs):
    SomeModel.objects.create(
        name='Woohoo',
        slug='look_mom_no_signals',
    )

注意：如果你的信号处理程序使用dispatch_uid，你必须使用dispatch_uid arg。

Answer 2

您可以像Haystack那样在RealTimeSearchIndex中连接和断开信号，这似乎更标准：

from django.db.models import signals
signals.pre_save.disconnect(pre_save_model, sender=MyModel)
a.save()
signals.pre_save.connect(pre_save_model, sender=MyModel)

Answer 3

我没有测试过以下代码，但它应该可以工作：

from django.db.models.signals import pre_save


def save_without_the_signals(instance, *args, **kwargs):
    receivers = pre_save.receivers
    pre_save.receivers = []
    new_instance = instance.save(*args, **kwargs)
    pre_save.receivers = receivers
    return new_instance

它会使来自所有发件人的信号静音，但不仅仅是instance.__class__。

此版本仅禁用给定模型的信号：

from django.db.models.signals import pre_save
from django.dispatch.dispatcher import _make_id


def save_without_the_signals(instance, *args, **kwargs):
    receivers = []
    sender_id = _make_id(instance.__class__)
    for index in xrange(len(self.receivers)):
        if pre_save.receivers[index][0][1] == sender_id:
            receivers.append(pre_save.receivers.pop(index))
    new_instance = instance.save(*args, **kwargs)
    pre_save.receivers.extend(receivers)
    return new_instance

Answer 4

如果您只想断开连接并重新连接一个自定义信号，则可以使用以下代码：

def disconnect_signal(signal, receiver, sender):
    disconnect = getattr(signal, 'disconnect')
    disconnect(receiver, sender)

def reconnect_signal(signal, receiver, sender):
    connect = getattr(signal, 'connect')
    connect(receiver, sender=sender)

通过这种方式你可以做到这一点：

disconnect_signal(pre_save, pre_save_model, MyModel)
a.save()
reconnect_signal(pre_save, pre_save_model, MyModel)

Answer 5

我需要在单元测试期间防止某些信号被触发，所以我根据qris的回复制作了一个装饰器：

$('#sidebar').css({'position':'fixed',
                   'top': '100px',
                   'left': '69.5%',
                   'width': '20%'});

使用它很简单：

from django.db.models import signals

def prevent_signal(signal_name, signal_fn, sender):
    def wrap(fn):
        def wrapped_fn(*args, **kwargs):
            signal = getattr(signals, signal_name)
            signal.disconnect(signal_fn, sender)
            fn(*args, **kwargs)
            signal.connect(signal_fn, sender)
        return wrapped_fn
    return wrap

断开模型的信号并在django中重新连接

5 个答案: