What are Django model validators and how do I use them?

What are Django model validators and how do I use them?

Django model validators are functions that validate the data before saving it to the database. You can use built-in validators or create custom ones.

Can you give me an example of a custom validator?

Sure! Here's a simple custom validator that checks if a value is positive:

from django.core.exceptions import ValidationError

def validate_positive(value):
    if value <= 0:
        raise ValidationError('Value must be positive.')

How do I apply this validator to a model field?

You can apply it by using the validators argument in your model field definition:

from django.db import models

class MyModel(models.Model):
    positive_number = models.IntegerField(validators=[validate_positive])

What happens if the validation fails?

If the validation fails, a ValidationError will be raised, and the data will not be saved to the database.