What are Django model field validators?

What are Django model field validators?

Django model field validators are functions that validate the data before it is saved to the database. They ensure that the data meets certain criteria.

Can you give me an example of a custom validator?

Sure! You can create a custom validator by defining a function that raises a ValidationError if the data is invalid. For example:

from django.core.exceptions import ValidationError

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

How do I use this validator in a model?

You can use the custom validator in your model field like this:

from django.db import models

class MyModel(models.Model):
    my_field = 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. You can catch this error in your forms or views to provide feedback to the user.