[Django] How to Reset Migrations

• Scenario 1:
  The project is still in the development environment and you want to perform a full clean up. You don't mind throwing the whole database away.

1. Remove the all migrations files within your project
   Go through each of your projects apps migration folder and remove everything inside, except the __init__.py file.

   Or if you are using a unix-like OS you can run the following script (inside your project dir):

   find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
   find . -path "*/migrations/*.pyc"  -delete

2. Drop the current database, or delete the db.sqlite3 if it is your case.
3. Create the initial migrations and generate the database schema:

   python manage.py makemigrations
   python manage.py migrate

   And you are good to go.

• Scenario 2:
  You want to clear all the migration history but you want to keep the existing database.

1. Make sure your models fits the current database schema
   The easiest way to do it is trying to create new migrations:

   python manage.py makemigrations

   If there are any pending migration, apply them first.

   If you see the message:

   No changes detected

   You are good to go.

2. Clear the migration history for each app
   Now you will need to clear the migration history app by app.

   First run the showmigrations command so we can keep track of what is going on:

   $ python manage.py showmigrations

   Result:

   admin
   [X] 0001_initial
   [X] 0002_logentry_remove_auto_add
   auth
   [X] 0001_initial
   [X] 0002_alter_permission_name_max_length
   [X] 0003_alter_user_email_max_length
   [X] 0004_alter_user_username_opts
   [X] 0005_alter_user_last_login_null
   [X] 0006_require_contenttypes_0002
   [X] 0007_alter_validators_add_error_messages
   contenttypes
   [X] 0001_initial
   [X] 0002_remove_content_type_name
   core
   [X] 0001_initial
   [X] 0002_remove_mymodel_i
   [X] 0003_mymodel_bio
   sessions
   [X] 0001_initial

   Clear the migration history (please note that core is the name of my app):

   $ python manage.py migrate --fake core zero

   The result will be something like this:

   Operations to perform:
   Unapply all migrations: core
   Running migrations:
   Rendering model states... DONE
   Unapplying core.0003_mymodel_bio... FAKED
   Unapplying core.0002_remove_mymodel_i... FAKED
   Unapplying core.0001_initial... FAKED

   Now run the command showmigrations again:

   $ python manage.py showmigrations

   Result:

   admin
   [X] 0001_initial
   [X] 0002_logentry_remove_auto_add
   auth
   [X] 0001_initial
   [X] 0002_alter_permission_name_max_length
   [X] 0003_alter_user_email_max_length
   [X] 0004_alter_user_username_opts
   [X] 0005_alter_user_last_login_null
   [X] 0006_require_contenttypes_0002
   [X] 0007_alter_validators_add_error_messages
   contenttypes
   [X] 0001_initial
   [X] 0002_remove_content_type_name
   core
   [ ] 0001_initial
   [ ] 0002_remove_mymodel_i
   [ ] 0003_mymodel_bio
   sessions
   [X] 0001_initial

   You must do that for all the apps you want to reset the migration history.

3. Remove the actual migration files.
   Go through each of your projects apps migration folder and remove everything inside, except for the __init__.py file.

   Or if you are using a unix-like OS you can run the following script (inside your project dir):

   find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
   find . -path "*/migrations/*.pyc"  -delete

   PS: The example above will remove all the migrations file inside your project.

   Run the showmigrations again:

   $ python manage.py showmigrations

   Result:

   admin
   [X] 0001_initial
   [X] 0002_logentry_remove_auto_add
   auth
   [X] 0001_initial
   [X] 0002_alter_permission_name_max_length
   [X] 0003_alter_user_email_max_length
   [X] 0004_alter_user_username_opts
   [X] 0005_alter_user_last_login_null
   [X] 0006_require_contenttypes_0002
   [X] 0007_alter_validators_add_error_messages
   contenttypes
   [X] 0001_initial
   [X] 0002_remove_content_type_name
   core
   (no migrations)
   sessions
   [X] 0001_initial

4. Create the initial migrations

   $ python manage.py makemigrations

   Result:

   Migrations for 'core':
   0001_initial.py:
   - Create model MyModel

5. Fake the initial migration
   In this case you won’t be able to apply the initial migration because the database table already exists. What we want to do is to fake this migration instead:

   $ python manage.py migrate --fake-initial

   Result:

   Operations to perform:
   Apply all migrations: admin, core, contenttypes, auth, sessions
   Running migrations:
   Rendering model states... DONE
   Applying core.0001_initial... FAKED

   Run showmigrations again:

   admin
   [X] 0001_initial
   [X] 0002_logentry_remove_auto_add
   auth
   [X] 0001_initial
   [X] 0002_alter_permission_name_max_length
   [X] 0003_alter_user_email_max_length
   [X] 0004_alter_user_username_opts
   [X] 0005_alter_user_last_login_null
   [X] 0006_require_contenttypes_0002
   [X] 0007_alter_validators_add_error_messages
   contenttypes
   [X] 0001_initial
   [X] 0002_remove_content_type_name
   core
   [X] 0001_initial
   sessions
   [X] 0001_initial

https://simpleisbetterthancomplex.com/tutorial/2016/07/26/how-to-reset-migrations.html