Django: running code on every startup but after database is migrated

Question

I thought there was an easy answer to this in recent versions of Django but I can\'t find it.

I have code that touches the database. I want it to run every time Django s

Answer 1

I would suggest the connection_created signal, which is:

Sent when the database wrapper makes the initial connection to the database. This is particularly useful if you’d like to send any post connection commands to the SQL backend.

So it will execute the signal's code when the app connects to the database at the start of the application's cycle.

It will also work within a multiple database configuration and even separate the connections made by the app at initialization:

connection
The database connection that was opened. This can be used in a multiple-database configuration to differentiate connection signals from different databases.

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Note:
You may want to consider using a combination of post_migrate and connection_created signals while checking inside your AppConfig.ready() if a migration happened (ex. flag the activation of a post_migrate signal):

from django.apps import AppConfig
from django.db.models.signals import post_migrate, connection_created
# OR for Django 2.0+
# django.db.backends.signals import post_migrate, connection_created

migration_happened = false

def post_migration_callback(sender, **kwargs):
    ...
    migration_happened = true


def init_my_app(sender, connection):
    ...


class MyAppConfig(AppConfig):
    ...

    def ready(self):
        post_migrate.connect(post_migration_callback, sender=self)

        if !migration_happened:
            connection_created.connect(init_my_app, sender=self)