Django extension to allow working with 'clusters' of models as a single unit, independently of the database

If you had a data model like this: class Band(models.Model): name = models.CharField(max_length=255) class BandMember(models.Model): band = models.ForeignKey('Band', related_name='members', on_delete=models.CASCADE) name = models.CharField(max_length=255) wouldn’t it be nice if you could construct bundles of objects like this, independently of the database: beatles = Band(name='The Beatles') beatles.members = [ BandMember(name='John Lennon'), BandMember(name='Paul McCartney'), ] Unfortunately, you can’t. Objects need to exist in the database for foreign key relations to work: IntegrityError: null value in column "band_id" violates not-null constraint But what if you could? There are all sorts of scenarios where you might want to work with a ‘cluster’ of related objects, without necessarily holding them in the database: maybe you want to render a preview of the data the user has just submitted, prior to saving. Maybe you need to construct a tree of things, serialize