How can I call a clean method before get_or_create saves to the database?

Question

I've got a model in Django in which some data is frequently invalid. Usually I call a clean() method that I've written to deal with these situations, however, get_or_create() seems to call save() before I get a chance to call clean().

How can clean my data before get_or_create() attempts to write to the database?

Here's the relevant parts of my model:

class Article(models.Model):
    optional_attribute = models.CharField(max_length = 250)

    def clean(self):
        if not self.optional_attribute:
            self.optional_attribute = 'Default'

Answer 1

It might be more appropriate to override the save method:

class Article(models.Model):
    optional_attribute = models.CharField(max_length = 250)

    def save(self, *args, **kwargs):
        if not self.optional_attribute:
            self.optional_attribute = 'Default'
        super(Article, self).save(*args, **kwargs)

Alternatively, you could use a pre_save signal handler:

from django.db.models.signals import pre_save

class Article(models.Model):
    optional_attribute = models.CharField(max_length = 250)

    @classmethod
    def pre_save_handler(cls, sender, instance, **kwargs):
        if not instance.optional_attribute:
            instance.optional_attribute = 'Default'

pre_save.connect(Article.pre_save_handler, sender=Article)

If you want to retain your clean method, you could simply use one of these techniques and call your clean method from within.

Answer 2

The get_or_create method is just a shortcut. If you want to clean the object, you can write your code slightly more verbosely.

try:
    article = Article.objects.get(**params)
except Article.DoesNotExist:
    article = Article(**params) 
    article.full_clean()
    article.save()