Converts the collation and character set of a database using a Django migration.

migrate_collation.py

"""
Converts the *collation* and *character set* of a database using a Django
migration. Data in the tables is converted if needed.

"""

from django.db import migrations


def get_conversion_function(collation, character_set='utf8'):
	"""
	Returns a function that sets the given *collation* and *character_set*.

	Args:
		collate: e.g. `utf8_general_cs`, `utf8_general_ci` or `utf8_bin`…
		character_set: e.g. `utf8`, `latin1`…

	"""

	def alter_collation_from_migration(apps, schema_editor):
		"""
		Sets *collation* and *character_set* for a database and its tables.

		Also converts data in the tables if necessary.

		"""
		with schema_editor.connection.cursor() as cursor:
			# set for database
			print('Altering database…')
			cursor.execute(
				f'ALTER DATABASE CHARACTER SET {character_set} COLLATE {collation};'
			)
			# set for tables (and convert data)
			cursor.execute(
				'SHOW TABLES;'
			)
			for table, in cursor.fetchall():
				print(f'Altering table `{table}`…')
				cursor.execute(
					f'ALTER TABLE {table} CONVERT TO CHARACTER '
					f'SET {character_set} COLLATE {collation}'
				)

	return alter_collation_from_migration


class Migration(migrations.Migration):
	"""
	Runs :func:`alter_collation_from_migration` with the given args.

	You need to set the :attr:`dependencies`. To figure out what to fill in run
	``django-admin makemigrations myapp --empty``.

	"""
	dependencies = [
		# Needs to be filled!
	]
	operations = [
		migrations.RunPython(get_conversion_function('utf8_general_ci')),
	]