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2018-01-08 Django

Django Signals

Django Signals#

Well what are they? They are hooks that you can listen for in your application and do a specific task when they occur.

You can check the Signal Docs for a more detailed explanation

There are alot of built-in signals

Using Signals Example with User Authentication Signals#

In this example we will be catching the user logout signal with the django.contrib.auth.signal.user_logged_out and adding a django message

NB First thing to do is make sure the app knows about the signals

  1. Create a signals.py file

  2. You need to import your signals into <app_label>/apps.py

    from django.apps import AppConfig

class UsersConfig(AppConfig):
    name = 'users'

    def ready(self):
        import users.signals

  3. Make sure the Config is loaded in __init__.py:

    default_app_config = '<app_name>.apps.<AppConfig>'

  4. In signals.py create your signal receiver

    Remember the parameters available are specified in built-in signal

    from django.contrib.auth.signals import user_logged_out
from django.dispatch import receiver

@receiver(user_logged_out)
def add_message_on_logout(sender, request, user, **kwargs):
    messages.info(request, 'You have been logged out.')

Alternatively you can connect to signals without the decorator:

    def add_message_on_logout(sender, request, user, **kwargs):
        messages.info(request, 'You have been logged out.')

    user_logged_out.connect(add_message_on_logout)

Source#

Stackoverflow Signals