How can I use Django model forms for advanced validation?

How can I use Django model forms for advanced validation?

You can use Django's built-in validation methods or create custom validators in your model forms.

Can you show me an example of a custom validator?

Sure! You can define a custom validator function and use it in your form field like this: 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, like this: price = models.DecimalField(validators=[validate_positive]).

What if I want to validate multiple fields together?

You can override the clean method in your form to validate multiple fields together and raise a ValidationError if needed.