Case insensitive unique model fields in Django?

Question

I have basically a username is unique (case insensitive), but the case matters when displaying as provided by the user.

I have the following requirements:

Answer 1

Since a username is always lowercase, it's recommended to use a custom lowercase model field in Django. For the ease of access and code-tidiness, create a new file fields.py in your app folder.

from django.db import models
from django.utils.six import with_metaclass

# Custom lowecase CharField

class LowerCharField(with_metaclass(models.SubfieldBase, models.CharField)):
    def __init__(self, *args, **kwargs):
        self.is_lowercase = kwargs.pop('lowercase', False)
        super(LowerCharField, self).__init__(*args, **kwargs)

    def get_prep_value(self, value):
        value = super(LowerCharField, self).get_prep_value(value)
        if self.is_lowercase:
            return value.lower()
        return value

Usage in models.py

from django.db import models
from your_app_name.fields import LowerCharField

class TheUser(models.Model):
    username = LowerCharField(max_length=128, lowercase=True, null=False, unique=True)

End Note : You can use this method to store lowercase values in the database, and not worry about __iexact.