How to override max length of username in Django by creating a custom model

Question

I have a problem. I'm using Django 1.7, and have already made a custom user model, that inherits Django's abstract user like this:

class CustomUser(AbstractUser, BaseModel):

Now they say in here Django-ticket, that I could avoid the problem of username's max_length being 30, by creating a custom user. Well, I already have a custom user, so it should be easy right? How I tried to do it was:

class CustomUser(AbstractUser, BaseModel):

      username = models.CharField(max_length=70, unique=True, db_index=True)

Now when I try to make migrations for changing this field, it results in an error: django.core.exceptions.FieldError: Local field 'username' in class 'CustomUser' clashes with field of similar name from base class 'AbstractUser'

What am I doing wrong? How could I solve this problem? I have data that should be migrated, so I cannot empty database.

Answer 1

If you want it to be more flexible inherit from AbstractBaseUser instead, you will be able to specify your own username field that way, e.g.

class User(AbstractBaseUser):
    email = models.EmailField(
        verbose_name='email address',
        max_length=255,
        unique=True,
    )

    is_active = models.BooleanField(default=True)
    is_admin = models.BooleanField(default=False)

    date_joined = models.DateTimeField(
        verbose_name=_('date created'),
        auto_created=True,
        default=timezone.now
    )

    objects = UserManager()

    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = []

https://docs.djangoproject.com/en/1.7/topics/auth/customizing/#specifying-a-custom-user-model