How is Django apps.py supposed to be used? - django

Question

I'm using django 1.10.5
It seems that the apps.py file in app1 is not imported unless I explicitely set default_app_config = 'app1.apps.App1Config' in __init__ for that module.
Yet, in the docs I'm reading "New applications should avoid default_app_config. Instead they should require the dotted path to the appropriate AppConfig subclass to be configured explicitly in INSTALLED_APPS."
I'm reading that as including the module in INSTALLED_APPS like
INSTALLED_APPS = (
'...',
'app1',
)
And I do have that.
Maybe I'm confused by the language "dotted path to the appropriate AppConfig subclass" and maybe there's more to it than listing the main module?
My specific use is that I want to import handlers.py so it will be included in the application because it has some signal receivers that need to be listening.
To do that, I followed the advice in the docs which says "In practice, signal handlers are usually defined in a signals submodule of the application they relate to. Signal receivers are connected in the ready() method of your application configuration class. If you’re using the receiver() decorator, simply import the signals submodule inside ready()."
# apps.py
from django.apps import AppConfig
class App1Config(AppConfig):
name = 'app1'
def ready(self):
import app1.handlers
# handlers.py
from django.dispatch import receiver
from django.db.models.signals import post_save
from app1.models import App1
#receiver(post_save, sender=App1)
def say_you_did_something(sender, instance, **kwargs):
print("Action has been taken.")
But that does absolutely nothing...
Until I also add
# __init__.py
default_app_config = 'individual.apps.IndividualConfig'
Which is supposed to be avoided except for < 1.7?
So to restate the question in practical terms, what is the recommended way to make the project aware of the handlers.py file?

Answer 1

You've misunderstood the instruction. As it says, you need to include the dotted path to the AppConfig class itself in INSTALLED_APPS, not the app.
INSTALLED_APPS = (
'...',
'app1.apps.App1Config',
)

Answer 2

Replace
INSTALLED_APPS = (
'...',
'app1,
)
with
INSTALLED_APPS = (
'...',
'app1.apps.App1Config',
)
No need to add default_app_config in init.py
In the django 3.0 application documentation it is mentioned how to include dotted path.
Below is the excerpt from django application documentation https://docs.djangoproject.com/en/3.0/ref/applications/#django.apps.AppConfig.ready :
For application authors¶
If you’re creating a pluggable app called “Rock ’n’ roll”, here’s how you would provide a proper name for the admin:
# rock_n_roll/apps.py
from django.apps import AppConfig
class RockNRollConfig(AppConfig):
name = 'rock_n_roll'
verbose_name = "Rock ’n’ roll"
You can make your application load this AppConfig subclass by default as follows:
# rock_n_roll/__init__.py
default_app_config = 'rock_n_roll.apps.RockNRollConfig'
That will cause RockNRollConfig to be used when INSTALLED_APPS contains 'rock_n_roll'. This allows you to make use of AppConfig features without requiring your users to update their INSTALLED_APPS setting. Besides this use case, it’s best to avoid using default_app_config and instead specify the app config class in INSTALLED_APPS as described next.
Of course, you can also tell your users to put 'rock_n_roll.apps.RockNRollConfig' in their INSTALLED_APPS setting. You can even provide several different AppConfig subclasses with different behaviors and allow your users to choose one via their INSTALLED_APPS setting.