[DJUGL] Signals and AppConfig

Django User Group in London meetup and my talk about "Signals and AppConfig" Rick and Morty style!

Transcript

1. SIGNALS AND APPCONFIG DJUGL October 6, 2015
2. @anabalica
3. Let’s get schwifty with !
4. from django.db.models.signals import post_save from django.dispatch import receiver from myapp.models import MyModel @receiver(post_save, sender=MyModel) def my_handler(sender, **kwargs): pass # my_app/signals.py
5. from django.db.models.signals import pre_save from django.dispatch import receiver from myapp.models import MyModel @receiver(pre_save, sender=MyModel) def my_handler(sender, **kwargs): pass # my_app/signals.py
6. Django<1.7? make sure that the module it’s in gets imported early on so that the signal handling gets registered before any signals need to be sent
7. Django<1.7? make sure that the module it’s in gets imported early on so that the signal handling gets registered before any signals need to be sent
8. Django<1.7? this makes your app’s models.py a good place to put registration of signal handlers
9. from django.db import models from my_app import signals class MyModel(models.Model): pass # my_app/models.py
11. CIRCULAR IMPORTS
12. from my_app import signals # my_app/__init__.py
14. AppConfig to the rescue
15. AppConfig is a registry of installed apps and available models
16. >>> from django.apps import apps >>> apps.get_app_config('admin').verbose_name 'Admin'
17. from django.apps import AppConfig class RickNMortyConfig(AppConfig): name = "rick_n_morty" verbose_name = "Rick and Morty" # my_app/apps.py
18. INSTALLED_APPS = [ "my_app.apps.RickNMortyConfig", # ... ] # settings.py or default_app_config = "my_app.apps.RickNMortyConfig" # my_app/__init__.py
20. from django.apps import AppConfig class RickNMortyConfig(AppConfig): name = "rick_n_morty" verbose_name = "Rick and Morty” def ready(self): from my_app import signals # my_app/apps.py
21. • Loads the settings • Sets up logging • Initializes the application registry
22. • Imports each item from INSTALLED_APPS • Imports the models submodule if exists • Runs the ready() method of each app config