Django Generic Relations with ContentType

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey
 
class Comment(models.Model):
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')
    text = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
 
# Usage:
class Author(models.Model):
    name = models.CharField(max_length=100)
 
 
class Book(models.Model):
    title = models.CharField(max_length=200)
 
# Comments can attach to any model:
Comment.objects.create(content_object=author_instance, text='Great author!')
Comment.objects.create(content_object=book_instance, text='Excellent read!')