Django Rest Framework - Non Field Error Custom Message

Question

I have looked at this question but that doesn't really tell me about non-field errors.

My Model is:

class DeviceContact(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    contact_sid = models.CharField(max_length=75, db_index=True)
    contact_name = models.CharField(max_length=200)
    contact_email = models.CharField(max_length=250, db_index=True)
    contact_type = models.CharField(max_length=200, default='mobile')

    class Meta:
        unique_together = ("contact_sid", "contact_email", "contact_name")


class DeviceContactSerializer(serializers.ModelSerializer):
    class Meta:
        model = DeviceContact
        fields = ('contact_sid', 'contact_name', 'contact_email', 'contact_type')

How do I return a custom error message when the unique_together condition fails?

score 2 · Accepted Answer · answered May 24 '15 at 00:10

When you have unique_together set on a model, the serializer will automatically generate a UniqueTogetherValidator that is used to check their uniqueness. You can confirm this by looking at the output of the serializer, and introspecting what Django REST framework automatically generates:

print(repr(DeviceContractSerializer()))

You can then alter the validators that are set to include your custom UniqueTogetherValidator with a custom message argument set up.

UniqueTogetherValidator(
    queryset=DeviceContract.objects.all(),
    fields=('contact_sid', 'contact_email', 'contact_name', ),
    message='This was not a unique combination within the system, pick a different one.'
)

This is exactly what I was looking for! – blue_zinc May 31 '15 at 14:38 — blue_zinc, May 31 '15 at 14:38
how to change `non_field_errors` key to specific one? – Susaj S N Jun 29 '20 at 09:25 — Susaj S N, Jun 29 '20 at 09:25

score 1 · Answer 2 · answered May 22 '15 at 17:05

1

How about overriding the DeviceContact's save method, intercepting the exception, and then re-throwing it to your liking?

class MySuperDuperException(Exception):
    pass

class DeviceContact(models.Model):
    [...]

    def save(self, *args, **kwargs):
        try:
            super(DeviceContact,self).save(*args,**kwargs)
        catch DeviceContact.IntegrityError as e:
            throw MySuperDuperException()

answered May 22 '15 at 17:05

Ross Rogers

23,523
27
108
164

interesting way of doing it. is there a way of doing this without touching the actual model? – blue_zinc May 23 '15 at 15:30
I believe the serializer has a save API as well. You may be able to do your wrappering there. – Ross Rogers May 27 '15 at 12:00

Django Rest Framework - Non Field Error Custom Message

2 Answers2