`preference_updated` signal not triggered when updating preferences via `PreferenceViewSet`

[KrYpTeD974]

Hello,

It seems that I've found an issue with the preference_updated signal in the latest version of django-dynamic-preferences.

Problem: The preference_updated signal is not triggered when I update a preference using the PreferenceViewSet or PerInstancePreferenceViewSet.

Steps to reproduce:

1. Register a signal receiver:

   from django.dispatch import receiver
   from dynamic_preferences.signals import preference_updated
   
   @receiver(preference_updated)
   def my_signal_receiver(sender, section, name, old_value, new_value, **kwargs):
       print("Preference {} in section {} changed from {} to {}".format(
           name, section, old_value, new_value))

2. Use the PreferenceViewSet to update a specific instance preference.
3. Observe that the preference_updated signal is not emitted after the update.

Expected behavior: I expected the preference_updated signal to be triggered, as it seems to be the case for other preference update methods.

Possible solution Add the following code to the PreferencesViewSet:

    def perform_update(self, serializer):
        old_value = serializer.instance.value
        super().perform_update(serializer)
        preference_updated.send(
            sender=self.__class__,
            section=serializer.instance.section,
            name=serializer.instance.name,
            old_value=old_value,
            new_value=serializer.instance.value,
        )

Environment:

• django-dynamic-preferences version: Latest version (v1.16.0).
• Django version: 5.1.2

[agateblue]

Hi @KrYpTeD974, this does indeed look like a bug. Your suggested fix would work for updating individual preferences but not with the bulk endpoint.

I think adding the signal logic in the serializer here : https://github.com/agateblue/django-dynamic-preferences/blob/develop/dynamic_preferences/api/serializers.py#L64 would work for both use cases. I'd be happy to review and merge a pull request implementing this!

[KrYpTeD974]

Indeed, ok fine ! I'll will try to submit a PR.