Django max_length for IntegerField

Question

I have this model field:

id_student = models.PositiveIntegerField(primary_key=True, max_length=10) 

The max_length restriction doesn't work. I can log in to the admin and create a student with an id with more than 10 chars. How can I solve this?

Answer 1

Django ignores max_length for integer fields, and will warn you in Django 1.8+. See ticket 23801 for more details.

You can either use a max value validator,

from django.core.validators import MaxValueValidator  class MyModel(models.Model):     ...     id_student = models.PositiveIntegerField(primary_key=True, validators=[MaxValueValidator(9999999999)]) 

or use a CharField to store the id, and use a regex validator to ensure that the id is entirely made of digits. This would have the advantage of allowing ids that start with zero.

from django.core.validators import RegexValidator  class MyModel(models.Model):     ...     id_student = models.CharField(primary_key=True, max_length=10, validators=[RegexValidator(r'^\d{1,10}$')])