gd/config/models.py

from django.db import models

class Config(models.Model):
    indice = models.CharField(max_length=32,null=False)
    valore = models.CharField(max_length=256,null=True)
    class Meta:
      constraints = [ models.UniqueConstraint(fields=['indice'], name="unique-indice") ]
      indexes = [ models.Index(fields=['indice']) ]