Question

In a model I usually put a “uuid” field for friendly URI, also a “slug” field.

Say I have a model named “SomeModel”, by overriding its save() method, I can generate a uuid and a slug when it’s being saved:

class SomeModel(models.Model):
    ...
    def save(self, *args, **kwargs):
        if not self.uuid:
            uuid = shortuuid.uuid()[:10]
            while SomeModel.objects.filter(uuid=uuid).exists():
                uuid = shortuuid.uuid()[:10]
            self.uuid = uuid
        if not self.slug:
            self.slug = slugify(self.title)[:500].rstrip('-')
        super(SomeModel, self).save(*args, **kwargs)

It works well on regular model. Now I’d like to have an abstract model:

class SomeAbstractModel(models.Model):
    class Meta:
        abstract = True
    def save(self, *args, **kwargs):
        ...

And then:

class SomeModel(SomeAbstractModel):
    class Meta(SomeAbstractModel.Meta):
        ...

The problem is, in the abstract model, looks like I cannot just simply replace

while SomeModel.objects.filter(uuid=uuid).exists():

with

while SomeAbstractModel.objects.filter(uuid=uuid).exists():

because abstract model doesn’t have a manager.

I was wondering in this case, how can I avoid having redundant code in all models’ save() methods. Also I’m not sure if

while SomeModel.objects.filter(uuid=uuid).exists():

is the best practice to check if an uuid exists or not.

Answer 1

Not sure if it is the prettiest way in town but this should work:

while self.__class__.objects.filter(...):
    pass