Consolidating multiple post_save signals with one receiver

Question

So I read the Django source code (post 1.5) that you can now register multiple multiple signals to a receiver function:

def receiver(signal, **kwargs):
    \         


        

Answer 1

Per the Django documentation on receivers, receivers by default do not need to be connected to a specific sender. So what you're describing is default Django functionality.

In other words, to do this using the @receiver decorator you simply don't specify a sender in the decorator. For example:

@receiver(post_save) # instead of @receiver(post_save, sender=Rebel)
def set_winner(sender, instance=None, created=False, **kwargs):
    list_of_models = ('Rebel', 'Stormtrooper', 'Battleground')
    if sender.__name__ in list_of_models: # this is the dynamic part you want
        if created: # only run when object is first created
            ... set the winner ...

This assumes models that look like:

class Rebel(models.Model):
    ...

class Stormtrooper(models.Model):
    ...

class Battleground(models.Model):
    ...

Answer 2

You can use that using @receiver decorator:

@receiver(post_save, sender=Model1)
@receiver(post_save, sender=Model2)
@receiver(post_save, sender=Model3)
def my_signal_handle(sender , **kwargs)
    # some code here

Answer 3

You can skip model_name and you will connect to all models post_save. Then you can filter if you are in right model in the handler:

post_save.connect(foo)

def foo(sender, **kwargs):
    if sender not in [FooModel, BarModel]:
        return
    ... actual code ...

or you can filter based on field in model:

def foo(sender, **kwargs):
    if not getattr(sender, 'process_by_foo', False):
        return
    ... actual code ...

Answer 4

def receiver_with_multiple_senders(signal, senders, **kwargs):
    """
    Based on django.dispatch.dispatcher.receiver

    Allows multiple senders so we can avoid using a stack of
    regular receiver decorators with one sender each.
    """

    def decorator(receiver_func):
        for sender in senders:
            if isinstance(signal, (list, tuple)):
                for s in signal:
                    s.connect(receiver_func, sender=sender, **kwargs)
            else:
                signal.connect(receiver_func, sender=sender, **kwargs)

        return receiver_func

    return decorator