REST django field validator based on other field in same model

Question

How do I validate the model attributes with validator based on other field in same model using django ModelSerializer. Example model code:

class LeadSerializer(serializers.ModelSerializer):
    class Meta:
        model = Lead
        fields = (
            'name','mobile','email','source',
            'referred_by_biz',
            'referred_by_ap')

If source entered is 'B', then referred_by_biz'(foreignkey value) cannot be blank and if source is 'A', then 'referred_by_ap' cannot be blank/null (foreignkey). How can I accomplish this at usign validate method? I have just started using REST framework. I am using curl to get the url for the same.

Answer 1

Something like this should probably work :

def validate(self, attrs):
    if attrs['source'] == 'A' and attrs['referred_by_ap'] == '':
        raise serializers.ValidationError('referred_by_ap cannot be blank')
    if attrs['source'] == 'B' and attrs['referred_by_biz'] == '':
        raise serializers.ValidationError('referred_by_biz cannot be blank')
    return attrs