old_contents: from rest_framework.serializers import ModelSerializer
  
  from .models import Stage, PaymentInfo, Price, AccommodationOption, EssayTopic, ProjectTopic
  
  
  class StageSerializer(ModelSerializer):
      class Meta:
          model = Stage
          fields = (
              'current_stage',
          )
  
  
  class PaymentInfoSerializer(ModelSerializer):
      class Meta:
          model = PaymentInfo
          exclude = (
              'id',
          )
  
  
  class PriceSerializer(ModelSerializer):
      class Meta:
          model = Price
          fields = (
              'code',
              'description',
              'price_krw',
              'price_usd',
          )
  
  
  class AccommodationOptionSerializer(ModelSerializer):
      class Meta:
          model = AccommodationOption
          fields = (
              'code',
              'description',
              'price_krw',
              'price_usd',
              'capacity',
          )
  
  
  class EssayTopicSerializer(ModelSerializer):
      class Meta:
          model = EssayTopic
          fields = (
              'number',
              'title',
              'description',
          )
  
  
  class ProjectTopicSerializer(ModelSerializer):
      class Meta:
          model = ProjectTopic
          fields = (
              'number',
              'title',
          )
  
new_contents: from rest_framework.serializers import ModelSerializer
  
  from .models import Stage, PaymentInfo, Price, AccommodationOption, EssayTopic, ProjectTopic
  
  
  class StageSerializer(ModelSerializer):
      class Meta:
          model = Stage
          fields = (
              'current_stage',
          )
  
  
  class PaymentInfoSerializer(ModelSerializer):
      class Meta:
          model = PaymentInfo
          exclude = (
              'id',
          )
  
  
  class PriceSerializer(ModelSerializer):
      class Meta:
          model = Price
          fields = (
              'code',
              'description',
              'price_krw',
              'price_usd',
          )
  
  
  class AccommodationOptionSerializer(ModelSerializer):
      class Meta:
          model = AccommodationOption
          fields = (
              'id',
              'code',
              'description',
              'price_krw',
              'price_usd',
              'capacity',
          )
  
  
  class EssayTopicSerializer(ModelSerializer):
      class Meta:
          model = EssayTopic
          fields = (
              'number',
              'title',
              'description',
          )
  
  
  class ProjectTopicSerializer(ModelSerializer):
      class Meta:
          model = ProjectTopic
          fields = (
              'number',
              'title',
          )
  
subject: add id to AccommodationOptionSerializer