Django: Return serializer ValidationError in Model save() method

Question

I use django-rest-framework to create Rest API within Django framework. And it's possible to return any validationError beside serializer methods.

But, I was wondering is it possible to return errors from save() method of django model that be translated to django rest validationError?

For example imagine I want to limit creating objects on a specific table. like this:

class CustomTable(models.Model):
    ... # modles fields go here

    def save():
        if CustomTable.objects.count() > 2:
             # Return a validationError in any serializer that is connected to this model.

Note I could use raise ValueError or raise ValidationError, but they all cause 500 error on endpoint. But i want to return a response in my api view that says for example 'limit reached'

Ken4scholars · Accepted Answer · 2021-09-22 13:41:47Z

6

The DRF ValidationError is handled in the serializer so you should catch any expected errors when calling your model's save method and use it to raise a ValiddationError.

For example, you could do this in your serializer's save method:

def save(self, **kwargs):
    try:
        super().save(**kwargs)
    except ModelError as e:
        raise serializers.ValidationError(e)

Where ModelError is the error you're raising in your model

edited Sep 22, 2021 at 13:41

answered Jan 6, 2019 at 12:22

Ken4scholars

6,2962 gold badges23 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

AjayShelar · Accepted Answer · 2019-01-06 12:49:41Z

1

There's are two to three ways to do this

1.Using clean method.

class CustomTable(models.Model):
    ... # modles fields go here

    def clean(self):
     if CustomTable.objects.count() > 2:
                raise ValidationError(_('custom table can not have more than two entries.'))

Using Signals.

@receiver(pre_save, sender= CustomTable)
def limit(sender, **kwargs):
      if CustomTable.objects.count() > 2:
            raise ValidationError(_('Custom table can not have more than two entries.'))

answered Jan 6, 2019 at 12:49

AjayShelar

4624 silver badges6 bronze badges

1 Comment

Ebram Shehata Over a year ago

Signals is always better. Cauz it handles objects created in Django admin.

Collectives™ on Stack Overflow

Django: Return serializer ValidationError in Model save() method

2 Answers 2

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related