How can I create custom validators in Django serializers?

How can I create custom validators in Django serializers?

You can create custom validators in Django serializers by defining a function that raises a validation error if the data is invalid.

Can you show me an example of a custom validator?

Sure! Here's a simple example:

from rest_framework import serializers

class MySerializer(serializers.Serializer):
    name = serializers.CharField(validators=[validate_name])

def validate_name(value):
    if len(value) < 3:
        raise serializers.ValidationError('Name must be at least 3 characters long.')

What if I want to validate multiple fields together?

You can use the validate method in your serializer to validate multiple fields. Here's an example:

class MySerializer(serializers.Serializer):
    first_name = serializers.CharField()
    last_name = serializers.CharField()

    def validate(self, data):
        if data['first_name'] == data['last_name']:
            raise serializers.ValidationError('First name and last name cannot be the same.')
        return data

Are there built-in validators I can use?

Yes, Django REST Framework provides several built-in validators like UniqueValidator, MaxLengthValidator, and more. You can use them directly in your serializers.