[Fixed]-Django handwritten migrations altering auth

Well, there is a tricky way to do that:

# -*- coding: utf-8 -*-
from django.db.migrations import Migration as DjangoMigration, AlterField
from django.db.models import CharField


class Migration(DjangoMigration):
    dependencies = [
        # Specify other dependencies, if required.
        ('auth', '0006_require_contenttypes_0002')
    ]
    operations = [
        AlterField(
            model_name='User',
            name='username',
            field=CharField(max_length=120)
        )
    ]

    def mutate_state(self, project_state, preserve=True):
        """
        This is a workaround that allows to store ``auth``
        migration outside the directory it should be stored.
        """
        app_label = self.app_label
        self.app_label = 'auth'
        state = super(Migration, self).mutate_state(project_state, preserve)
        self.app_label = app_label
        return state

    def apply(self, project_state, schema_editor, collect_sql=False):
        """
        Same workaround as described in ``mutate_state`` method.
        """
        app_label = self.app_label
        self.app_label = 'auth'
        state = super(Migration, self).apply(project_state, schema_editor, collect_sql)
        self.app_label = app_label
        return state

Put this in your application’s migrations folder with a proper name, e.g. 0001_alter_auth_user_username.py.

I’m not sure, however, that this is a good approach.

Thanks @Ernest Ten.

In my case, I kept the dependency on:

dependencies = [
# Specify other dependencies, if required.
('auth', '0004_alter_user_username_opts')
]

Make sure you run “python manage.py migrate” to get this reflected to you db.