Signals - No Signalling! Boots-patching django to globally disable signals

Monkey-patch: a way for a program to extend or modify supporting system software locally - Wikipedia

Boots-patch: a monkey-patch to explicitly disable a intrinsict and usually unstoppable action (usually using three identical boolean tests to highlight the patch) - LegoStormtroopr

Django includes a signals framework that notifies reciever functions when specific actions take place through the use of signals. Probably, the most common of these is the post_save signal, which will frequently be caught by third-party apps to provide post save hooks in Django code. Unfortunately, these signals can interfere when trying to use Django’s loaddata command (as in my case) or during testing - and the recommended solution is to use wrappers around code or liberally use raw=True in Signal reciever code.

However, these only work when you have control over that code - which won’t work if you are using a third-party django app, which doesn’t do these things.

The only solution is to globally disable all signals using monkey-patching, which is shown below:

if os.environ.get('django_SIGNALS_NO_SIGNALLING', None) and \
   os.environ.get('django_SIGNALS_NO_SIGNALLING', None) and \
   os.environ.get('django_SIGNALS_NO_SIGNALLING', None):
    from django.dispatch.dispatcher import Signal

    def send(*args, **kwargs):
        pass
    def send_robust(*args, **kwargs):
        pass
    Signal.send = send
    Signal.send_robust = send_robust

Now, I think this goes beyond regular monkey-patching as this is patching to effectively disable a regular and expected action.

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Here, we disable the Django Signal object from signalling by overriding the Signal.send and Signal.send_robust methods with blank methods.

To check if the patch should be applied, there is an explicit check against the “Signals no signalling” enivronment 3 times, both to highlight the potentially dangerous behaviour and to reinforce the (terrible) Swiper/Boots-patching joke.

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In Dora the Explorer, Dora (and her monkey Boots) often encounter Swiper. Swiper’s raison d’être is to swipe thing, and will always Swipe things. The only way to override this intrinsic behaviour is to say “Swiper, no swiping” three times.

Just as Swiper exists to swipe, Django signals exist to signal - so by Boots-patching we really are changing the intrinsic and expected behaviour of the object.