[FIXED] django OneToOneField to abstract object

Issue

i want a field be OneToOneField to an abstract object, the abstract will be never used, instead will be used subclasses:

from django.db import models

class Abs(models.Model):
    useType = True
    absName = models.CharField(max_length=10, default='mickey', blank=True)

    class Meta:
        abstract = True

from django.db import models
from .abs import Abs

class Sub(Abs):
    useType = False
    name=models.CharField(max_length=10, default='', blank=True)

from django.db import models
from .abs import Abs

class ParentClass(models.Model):
    abs = models.OneToOneField(Abs, on_delete=models.CASCADE)

but when make makemigrations i receive following error:

books.ParentClass.abs: (fields.E300) Field defines a relation with model 'Abs', which is either not installed, or is abstract.
books.ParentClass.abs: (fields.E307) The field books.ParentClass.abs was declared with a lazy reference to 'books.abs', but app 'books' doesn't provide model 'abs'.

If Abs was a real object all works fine, but Abs should never be a real object, so i thought should be abstract, it's only a basket to common info/methods, an interface.

Is there a way to do that?

Many thanks

Solution

You cannot have any reference field(OneToOne, ManyToOne, ForeignKey) to an abstract class 'cause they have not a corresponding table in the database.

Keep the code as you have it but suppress the:

    class Meta:
            abstract = True

and it should be fine.

Your database will have an Abs table with all the Abs objects and their general attributes, and the specifications will hold the same objects with the extra attributes.

Answered By - 42WaysToAnswerThat