django - 断开模型的信号并在 django 中重新连接

Question

我需要对模型进行保存，但我需要在保存之前断开一些信号接收器。

我的意思是，

我有一个模型:

class MyModel(models.Model):
    ...

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

pre_save.connect(pre_save_model, sender=MyModel)

在代码的另一个地方我需要这样的东西:

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:如果您的信号处理程序使用 dispatch_uid，您必须使用 dispatch_uid arg。 p>