[Solved]-Automatic db router for migrations in django

by

4👍

✅

I don’t know of any way to do that automatically. However, a simple approach might be to write your own version of the migrate command that calls the Django migrate command multiple times with the appropriate --database and app arguments.

According to the author of Django migrations, this is a conscious design decision, so I wouldn’t expect it to change: “Just like syncdb, migrate only runs on one database at a time, so you must execute it individually for each database, as you suggest. This is by design.”

👤Kevin Christopher Henry

15👍

For anyone facing the issue I was having, here is what I finally settled on:

routers.py:

from django.conf import settings
class DatabaseAppsRouter(object):

    def db_for_read(self, model, **hints):
        #  your db routing

    def db_for_write(self, model, **hints):
        #  your db routing

    def allow_relation(self, obj1, obj2, **hints):
        #  your db routing

    def allow_syncdb(self, db, model):
        #  your db routing

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        if db in settings.DATABASE_APPS_MAPPING.values():
            return settings.DATABASE_APPS_MAPPING.get(app_label) == db
        elif app_label in settings.DATABASE_APPS_MAPPING:
            return False

settings.py

DATABASE_ROUTERS = ['project.routers.DatabaseAppsRouter']
DATABASE_APPS_MAPPING = {'contenttypes': 'default',
                     'auth': 'default',
                     'admin': 'default',
                     'sessions': 'default',
                     'messages': 'default',
                     'staticfiles': 'default',
                     'myapp': 'mydb',
                     }

this setup lets me to run two commands:

python manage.py migrate
python manage.py migrate --database=mydb

which is still one to many but at least now I cannot mistakenly migrate myapp to the default database which happened more times that I want to admit.

Warning – rant:

Up to this point I was finding the Django design to be quircky but very logical and programmer friendly, like python itself. But the way that migrations interact with multiple database setups is really inconvenient makes it so easy to flood your default database with unwanted tables.
Discussion linked by kevin in his answer shows that I am not the only one to have this kind of difficulties.

👤Raff89

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