old_contents: from rest_framework.serializers import ModelSerializer
  from rest_framework.fields import CharField, IntegerField
  from app.models import Connection
  
  class ConnectionSerializer(ModelSerializer):
      image_url = SerializerMethodField()
      vote_count = IntegerField()
      
      SerializerMethodField()
  
      class Meta:
          model = Connection
          fields = (
              'id', 'image_url', 'name', 'description',
              'vote_count', 'iframe_url',
          )
  
new_contents: from rest_framework.serializers import ModelSerializer, SerializerMethodField
  from rest_framework.fields import CharField, IntegerField
  from django.conf import settings
  
  from app.models import Connection
  
  class ConnectionSerializer(ModelSerializer):
      image_url = SerializerMethodField()
      vote_count = IntegerField()
      
      def get_image_url(self, obj):
          return '{}/{}'.format(settings.MEDIA_URL, obj.image_url)
  
      class Meta:
          model = Connection
          fields = (
              'id', 'image_url', 'name', 'description',
              'vote_count', 'iframe_url',
          )
  
subject: fix image