Django Migrations

• Migration in Django is to make changes to your models
• Like deleting, adding a field, etc. into your database schema.

6.1 Apply migration

• Makemigrations
  • Detect changes and prepare database to update
  • It creates migration in ‘my_app/migrations/0001_initial.py’
  • Shows if any changes has been made or not

# All apps
python manage.py makemigrations

# singl3 app
python manage.py makemigrations my_app

• Sqlmigrate
  • View the actual sql code that runs in database
  • We don’t need to know sql, just use model class in model.py file, which is a feature of Django ORM

python manage.py sqlmigrate my_app mig_file_name

• Migrate
  • Apply changes to DB, all tables are created/updated
  • The migrate command looks at the INSTALLED_APPS setting and
  • Creates any necessary database tables according to the database settings in your mysite/settings.py file

python manage.py migrate

6.2 Revert Migrations

• Check migrations files(applied/unapplied)
  • [X] - to show which migrations have been applied
  • [ ] - to shows unapplied migrations

# Show migration files of all apps
python manage.py showmigrations --list

# Show migration files of current app
python manage.py showmigrations accounts

• Revert
  1. Revert migration to old_state
  2. Delete the reverted migration_files
  3. python manage.py makemigrations
  4. python manage.py migrate

./manage.py migrate product 0013_productpricehikehistory 

# Revert all migrations to initial or start
./manage.py migrate my_app zero

Reference

• Undo Migration