how to get the value of the linked class in the model of djamgo code example

Example 1: create models in django

from django.db import models
# Create your models here.

class Contact(models.Model):
    name = models.CharField(max_length=50)
    email = models.CharField(max_length=50)
    contact = models.CharField(max_length=50)
    content = models.TextField()
    def __str__(self):
        return self.name + ' ' + self.email

Example 2: super in django manager

# First, define the Manager subclass.
class DahlBookManager(models.Manager):
    def get_queryset(self):
        return super().get_queryset().filter(author='Roald Dahl')

# Then hook it into the Book model explicitly.
class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.CharField(max_length=50)

    objects = models.Manager() # The default manager.
    dahl_objects = DahlBookManager() # The Dahl-specific manager.