How to squash recent Django migrations?

Question

In Django\'s migrations code, there\'s a squashmigrations command which: \"Squashes the migrations for app_label up to and including migratio

Answer 1

I created django-squash https://pypi.org/project/django-squash/ as a way to not have to deal with migrations on a per-app level or worse a per-app-specific-migration level, and handle it on a per-project level. The idea is to hopefully integrate it inside core Django at some point.

Basic idea:

• You have a product, nothing open source that other people enhance, but yours, your teams, you deal with it.
• After each release you want to squash all migrations you did in the past release and start a new because your product has evolved from what it was last release and your data model as well.
• You squash, it looks to see if you've squashed previously, if you have, it will deleted any VERY old migrations that have no business in your codebase anymore. Finally, create a new snapshot of your migrations, and keep what migrations you had around.
• You will do this every release/when ever you feel your tests are taking too long running all your migrations.

Example:

/app1/migrations/__init__.py
/app1/migrations/0001_initial.py
/app1/migrations/0002_created_user_model.py
/app1/migrations/0003_added_username.py
/app1/migrations/0004_added_password.py
/app1/migrations/0005_last_name.py

You've applied them all.

But every time you run your tests, every single one of those steps need to run, taking valuable time. So we squash. The new directory will look like this:

/app1/migrations/__init__.py
/app1/migrations/0001_initial.py
/app1/migrations/0002_created_user_model.py
/app1/migrations/0003_added_username.py
/app1/migrations/0004_added_password.py
/app1/migrations/0005_last_name.py
/app1/migrations/0006_squash.py

inside 0006_squash.py you will find a replaces = [..] with the names of migrations 1-5. You will also find a Migration.operations = [..] with everything you would expect if you deleted all your migrations and did a ./manage.py makemigrations + any RunSQL/RunPython with elidable=False. If you deploy to an environment that is missing any of migrations 1-5 it will apply it from source and not use 0006 AT ALL. (this is standard Django migrations)

Some time passes, now your migrations look like this:

/app1/migrations/__init__.py
/app1/migrations/0001_initial.py
/app1/migrations/0002_created_user_model.py
/app1/migrations/0003_added_username.py
/app1/migrations/0004_added_password.py
/app1/migrations/0005_last_name.py
/app1/migrations/0006_squash.py
/app1/migrations/0007_change_username_to_100_char.py
/app1/migrations/0008_added_dob.py

You squash again. This time the following will happen. Anything inside the replaces = [..] will be deleted. 0006_squash.py will be modified to have replaces be an empty list. Lastly the squash will be recreated with the new changes. All told, will look like this:

/app1/migrations/0006_squash.py
/app1/migrations/0007_change_username_to_100_char.py
/app1/migrations/0008_added_dob.py
/app1/migrations/0009_squash.py

Starting the cycle once again.