[Answered ]-Django – Dynamic unique test for a model field

I’m assuming that your use case is that you only care about uniqueness within some relation with a larger group – eg, you don’t need globally unique slugs, so unique=True is “too unique”, you only need unique slugs for each Category within a CategoryGroup.

I’d suggest overriding Category.save(). You can check self.pk to see if this is an insert or update, and if it’s insert, you can call your custom unique-check and slug-generation code before calling super(Category, self).save(*args, **kwargs).