Van's Migration Helper

Django commands to help with running Django migrations.

Installation

• Add the dependency to your environment:

  pip install vmigration-helper
  

• Add the app vmgration_helper.apps.VMigrationHelperConfig to your list of installed apps in your settings:

  INSTALLED_APPS = [
    ...
    'vmigration_helper.apps.VMigrationHelperConfig',
    ...
  ]
  

Commands

migration_records

Shows existing migration records in your django_migration table.

> python manage.py migration_records
    ID Applied                           App Name
     1 2024-12-06T18:15:03+0000 contenttypes 0001_initial
     2 2024-12-06T18:15:03+0000         auth 0001_initial
     3 2024-12-06T18:15:03+0000        admin 0001_initial
     4 2024-12-06T18:15:03+0000        admin 0002_logentry_remove_auto_add
     5 2024-12-06T18:15:03+0000        admin 0003_logentry_add_action_flag_choices
     6 2024-12-06T18:15:03+0000 contenttypes 0002_remove_content_type_name
     7 2024-12-06T18:15:03+0000         auth 0002_alter_permission_name_max_length
     8 2024-12-06T18:15:03+0000         auth 0003_alter_user_email_max_length
     9 2024-12-06T18:15:03+0000         auth 0004_alter_user_username_opts
    10 2024-12-06T18:15:03+0000         auth 0005_alter_user_last_login_null
    11 2024-12-06T18:15:03+0000         auth 0006_require_contenttypes_0002
    12 2024-12-06T18:15:03+0000         auth 0007_alter_validators_add_error_messages
    13 2024-12-06T18:15:03+0000         auth 0008_alter_user_username_max_length
    14 2024-12-06T18:15:03+0000         auth 0009_alter_user_last_name_max_length
    15 2024-12-06T18:15:03+0000         auth 0010_alter_group_name_max_length
    16 2024-12-06T18:15:03+0000         auth 0011_update_proxy_permissions
    17 2024-12-06T18:15:03+0000         auth 0012_alter_user_first_name_max_length
    18 2024-12-06T18:15:03+0000     sessions 0001_initial

> python manage.py migration_records --format csv
ID,Applied,App,Name
1,2024-12-06T18:15:03+0000,contenttypes,0001_initial
2,2024-12-06T18:15:03+0000,auth,0001_initial
3,2024-12-06T18:15:03+0000,admin,0001_initial
4,2024-12-06T18:15:03+0000,admin,0002_logentry_remove_auto_add
5,2024-12-06T18:15:03+0000,admin,0003_logentry_add_action_flag_choices
6,2024-12-06T18:15:03+0000,contenttypes,0002_remove_content_type_name
7,2024-12-06T18:15:03+0000,auth,0002_alter_permission_name_max_length
8,2024-12-06T18:15:03+0000,auth,0003_alter_user_email_max_length
9,2024-12-06T18:15:03+0000,auth,0004_alter_user_username_opts
10,2024-12-06T18:15:03+0000,auth,0005_alter_user_last_login_null
11,2024-12-06T18:15:03+0000,auth,0006_require_contenttypes_0002
12,2024-12-06T18:15:03+0000,auth,0007_alter_validators_add_error_messages
13,2024-12-06T18:15:03+0000,auth,0008_alter_user_username_max_length
14,2024-12-06T18:15:03+0000,auth,0009_alter_user_last_name_max_length
15,2024-12-06T18:15:03+0000,auth,0010_alter_group_name_max_length
16,2024-12-06T18:15:03+0000,auth,0011_update_proxy_permissions
17,2024-12-06T18:15:03+0000,auth,0012_alter_user_first_name_max_length
18,2024-12-06T18:15:03+0000,sessions,0001_initial

These are the records of migrations applied. The fields indicate:

• ID - the ID of the migration record
• Applied - when the migration was applied
• App - name of the Django app
• Name - name of the migration

Optional parameters:

• --format (console | csv) print the info in CSV or friendlier console format (default)
• --connection-name {connection} the connection name to use (default is django.db.DEFAULT_DB_ALIAS)

migration_current_id

Shows the ID of the latest migration record in your django_migration table.

> python manage.py migration_current_id
18

18 is the ID of the latest record as shown above.

Optional parameters:

• --connection-name {connection} the connection name to use (default is django.db.DEFAULT_DB_ALIAS)

migration_rollback

Roll-back (unapply) previously applied migrations after (but not including) the migration ID provided.

> python manage.py migration_rollback 2

The above will rollback migrations after 0001_initial of the auth app (ID 2). The helper will figure out and run the intermediate rollbacks for different Django apps (e.g. sessions, auth, contenttypes) to get us back to ID 2.

It will use the existing migration command (e.g. python manage.py migrate ...) for compatibility. There is no "clever" rewrite of anything.

Here's what it runs:

python manage.py migrate sessions zero
Operations to perform:
  Unapply all migrations: sessions
Running migrations:
  Rendering model states... DONE
  Unapplying sessions.0001_initial... OK

python manage.py migrate auth 0001_initial
Operations to perform:
  Target specific migration: 0001_initial, from auth
Running migrations:
  Rendering model states... DONE
  Unapplying auth.0012_alter_user_first_name_max_length... OK
  Unapplying auth.0011_update_proxy_permissions... OK
  Unapplying auth.0010_alter_group_name_max_length... OK
  Unapplying auth.0009_alter_user_last_name_max_length... OK
  Unapplying auth.0008_alter_user_username_max_length... OK
  Unapplying auth.0007_alter_validators_add_error_messages... OK
  Unapplying auth.0006_require_contenttypes_0002... OK
  Unapplying auth.0005_alter_user_last_login_null... OK
  Unapplying auth.0004_alter_user_username_opts... OK
  Unapplying auth.0003_alter_user_email_max_length... OK
  Unapplying auth.0002_alter_permission_name_max_length... OK

python manage.py migrate contenttypes 0001_initial
Operations to perform:
  Target specific migration: 0001_initial, from contenttypes
Running migrations:
  Rendering model states... DONE
  Unapplying contenttypes.0002_remove_content_type_name... OK

Now, the migration state is where the latest migration record is ID 2:

> python manage.py migration_records
    ID Applied                           App Name
     1 2024-12-06T18:15:03+0000 contenttypes 0001_initial
     2 2024-12-06T18:15:03+0000         auth 0001_initial

Optional parameters:

• --connection-name {connection} the connection name to use (default is django.db.DEFAULT_DB_ALIAS)

• --dry-run will print the commands but will not actually run them

• --migrate-cmd <command to run migrations> sets the command to run migrations with. The command must accept the app and migration name as the {app} and {name} placeholders, respectively.

  For example:

  --migrate-cmd "pipenv run python manage.py migrate {app} {name}" 
  

  can be used to have the command run migrations using pipenv.

  For example:

  > pipenv run python manage.py migration_rollback 0 --dry-run --migrate-cmd "pipenv run python manage.py migrate {app} {name}"
  pipenv run python manage.py migrate sessions zero
  pipenv run python manage.py migrate auth 0001_initial
  pipenv run python manage.py migrate contenttypes 0001_initial
  pipenv run python manage.py migrate admin zero
  pipenv run python manage.py migrate auth zero
  pipenv run python manage.py migrate contenttypes zero
  

migration_delete

Deletes an entry from Django's migration records. This command should be used only as a last resort to fix up migration records that cannot be rolled back. No migration up/down is performed; the record is simply removed from django_migrations.

NOTE also that migrations that depend on the record being deleted will be "broken" after the deletion, so this command should only be run on "leaf" migration records unless you plan to also delete other migration records that depend on the one being deleted.

python manage.py migration_delete myapp 0003_some_migration
Confirm deletion of myapp:0003_some_migration (yes or no): yes

The command above deletes the migration 0003_some_migration for the app myapp (after getting confirmation).

To delete without confirmation, use the --yes option:

python manage.py migration_delete myapp 0003_some_migration --yes

Optional parameters:

• --connection-name {connection} the connection name to use (default is django.db.DEFAULT_DB_ALIAS)
• --yes will proceed to deleting the record without asking for confirmation

Ideas for automation

Here's an idea for automating the deployment of your Django app using these utilities:

• Deploy new code
• Run migration_current_id and capture the current ID
• Run migration normally
• Run your automated tests normally
  • If tests pass, you're done!
  • If tests fail, and you need to rollback, run migration_rollback <captured ID>