I'd like the exact same thing as django.contrib.contenttypes.generic.GenericForeignKey, but OneToOne instead of ForeignKey. I thought an easy (albeit marginally inelegant) workaround was to add unique=True to the field in question, but that borks.
Use unique_together?
Any combination of the content_type field and the ID field is a unique identifier for one object, therefore 1 to 1.
http://docs.djangoproject.com/en/dev/ref/models/options/#unique-together
来源：https://stackoverflow.com/questions/4893823/how-can-i-make-and-enforce-a-generic-onetoone-relation-in-django