[Django]-The right place to keep my signals.py file in a Django project

If you’re using Django<=1.6 I’d recommend Kamagatos solution: just import your signals at the end of your models module.

For future versions of Django (>=1.7), the recommended way is to import your signals module in your app’s config ready() function:

my_app/apps.py

from django.apps import AppConfig

class MyAppConfig(AppConfig):
    name = 'my_app'

    def ready(self):
        import my_app.signals

my_app/__init__.py

default_app_config = 'my_app.apps.MyAppConfig'

To solve your problem you just have to import signals.py after your model definition. That’s all.

I also put signals in signals.py file and also have this code snippet that loads all signals:

# import this in url.py file !

import logging

from importlib import import_module

from django.conf import settings

logger = logging.getLogger(__name__)

signal_modules = {}

for app in settings.INSTALLED_APPS:
    signals_module = '%s.signals' % app
    try:
        logger.debug('loading "%s" ..' % signals_module)
        signal_modules[app] = import_module(signals_module)
    except ImportError as e:
        logger.warning(
            'failed to import "%s", reason: %s' % (signals_module, str(e)))

This is for project, I’m not sure if it works at app level.

In old Django versions would be fine to put the signals on the __init__.py or maybe in the models.py(although at the end models will be way to large for my taste).

With Django 1.9, it is better I think, to place the signals on a signals.py file and import them with the apps.py, where they are going to be loaded after loading the model.

apps.py:

from django.apps import AppConfig


class PollsConfig(AppConfig):
    name = 'polls'

    def ready(self):
        from . import signals  # NOQA

You can also divide your signals on signals.py and handlers.py in another folder within your model named signals as well, but for me that is just over engineering. Take a look at Placing Signals

This only applies if you have your signals in a separate signals.py file

In completely agree with the answer of @EricMarcos but it should be stated that the django docs explicitly advice not to use the default_app_config variable (although it is not wrong). For current versions, correct way would be:

my_app/apps.py

from django.apps import AppConfig

class MyAppConfig(AppConfig):
    name = 'my_app'

    def ready(self):
        import my_app.signals

settings.py

(Make sure you don’t just have your app name in installed apps but instead the relative path to your AppConfig)

INSTALLED_APPS = [
    'my_app.apps.MyAppConfig',
    # ...
]

I’m guessing that you’re doing that so your signals are registered, so that they’re found somewhere. I just put my signals right in a models.py file normally.

An alternative is to import the callback functions from signals.py and connect them in models.py:

signals.py

def pre_save_callback_function(sender, instance, **kwargs):
    # Do stuff here

model.py

# Your imports here
from django.db.models.signals import pre_save
from yourapp.signals import pre_save_callback_function

class YourModel:
    # Model stuff here
pre_save.connect(pre_save_callback_function, sender=YourModel)

Ps: Importing YourModel in signals.py will create a recursion; use sender, instead.

Ps2: Saving the instance again in the callback function will create a recursion. You can make a control argument in .save method to control it.