title: Django Rest Framework - Restrict FK entries
body: <p>I have 2 models, Post and Comments</p>
  
  <pre><code>class Post(models.Model):
      post_id = models.IntegerField(primary_key=True)
      ...
  
  class Comment(models.Model):
      post = models.ForeignField(Post, on_delete=models.CASCADE, related_name='comment_post')
      ...
  </code></pre>
  
  <p>I have made a serializer for post</p>
  
  <pre><code>class CommentSerializer(serializers.ModelSerializer):
      class Meta:
          model = Comment
          fields = '__all___'
  
  class PostSerializer(serializers.ModelSerializer):
      comments = CommentSerializer(many=True, source='comment_post')
  
      class Meta:
          model = Post
          fields = ('post_id', 'comments')
  </code></pre>
  
  <p>The PostSerializer gives all the comments on a particular post. </p>
  
  <p>I want to access 5 latest comments per post. (planning to use something like order_by('-comment_time')[:5])</p>
  
  <p>How can i do this in Django Rest Framework within PostSerializer?</p>
  
  <p>Thanks!</p>