title: Django Rest Framework: Get related specific model field in serializer from another model
body: <p>I'm trying to return a Response including data from 2 linked models, where I can get a specific field value from another model. The models are: </p>
  
  <pre><code>class Author(models.Model):
      author = models.CharField(max_length=200)
      author_created = models.DateTimeField(auto_now_add=True)
  
      class Meta:
          ordering = ('author_created',)
  
  class Book(models.Model):
      book_name = models.CharField(max_length=200)
      author_name = models.ForeignKey(Author, on_delete=models.CASCADE)
      book_created = models.DateTimeField(auto_now_add=True)
  
      class Meta:
          ordering = ('book_created',)
  </code></pre>
  
  <p>Serializers are:</p>
  
  <pre><code>class AuthorSerializer(serializers.ModelSerializer):
      class Meta:
          model = Author
          fields = ('id', 'author')
  
  class BookSerializer(serializers.ModelSerializer):
      name = AuthorSerializer(source='author_name')
      class Meta:
          model = Book
          fields = ('id', 'book_name','name')
  </code></pre>
  
  <p>My response shows like this:</p>
  
  <pre><code>[
      {
          "id": 1,
          "book_name": "Himu",
          "name": {
              "id": 1,
              "author": "Humayun Ahmed"
          }
      },
      {
          "id": 2,
          "book_name": "Shanta's family",
          "name": {
              "id": 2,
              "author": "Jafar Iqbal"
          }
      }
  ]
  </code></pre>
  
  <p>But i want to show it like this:</p>
  
  <pre><code>[
      {
          "id": 1,
          "book_name": "Himu",
          "name": {
              "author": "Humayun Ahmed"
          }
      },
      {
          "id": 2,
          "book_name": "Shanta's family",
          "name": {
              "author": "Jafar Iqbal"
          }
      }
  ]
  </code></pre>
  
  <p>How can i get this output?</p>