old_contents: from handover_api.models import Handover, Draft, DukeDSUser
  from django.contrib.auth.models import User
  from rest_framework import serializers
  
  
  class HandoverSerializer(serializers.HyperlinkedModelSerializer):
      project_id = serializers.StringRelatedField(source='project.project_id', read_only=True)
      from_user_id = serializers.StringRelatedField(source='from_user.dds_id', read_only=True)
      to_user_id = serializers.StringRelatedField(source='to_user.dds_id', read_only=True)
  
      class Meta:
          model = Handover
          fields = ('id','url','project_id','from_user_id','to_user_id','state')
  
  
  class DraftSerializer(serializers.HyperlinkedModelSerializer):
      project_id = serializers.StringRelatedField(source='project.project_id', read_only=True)
      from_user_id = serializers.StringRelatedField(source='from_user.dds_id', read_only=True)
      to_user_id = serializers.StringRelatedField(source='to_user.dds_id', read_only=True)
  
      class Meta:
          model = Draft
          fields = ('id','url','project_id','from_user_id','to_user_id','state')
  
  
  class UserSerializer(serializers.HyperlinkedModelSerializer):
      user_id = serializers.PrimaryKeyRelatedField(source='user', queryset=User.objects.all())
      class Meta:
          model = DukeDSUser
          fields = ('id', 'user_id','url','dds_id', 'api_key', 'full_name', 'email')
new_contents: from handover_api.models import Handover, Draft, DukeDSUser, DukeDSProject
  from django.contrib.auth.models import User
  from rest_framework import serializers
  
  
  class HandoverSerializer(serializers.HyperlinkedModelSerializer):
      project_id = serializers.SlugRelatedField(source='project', slug_field='project_id', queryset=DukeDSProject.objects.all())
      from_user_id = serializers.SlugRelatedField(source='from_user', slug_field='dds_id', queryset=DukeDSUser.api_users.all())
      to_user_id = serializers.SlugRelatedField(source='to_user', slug_field='dds_id', queryset=DukeDSUser.objects.all())
  
      class Meta:
          model = Handover
          fields = ('id','url','project_id','from_user_id','to_user_id','state')
  
  
  class DraftSerializer(serializers.HyperlinkedModelSerializer):
      project_id = serializers.StringRelatedField(source='project.project_id', read_only=True)
      from_user_id = serializers.StringRelatedField(source='from_user.dds_id', read_only=True)
      to_user_id = serializers.StringRelatedField(source='to_user.dds_id', read_only=True)
  
      class Meta:
          model = Draft
          fields = ('id','url','project_id','from_user_id','to_user_id','state')
  
  
  class UserSerializer(serializers.HyperlinkedModelSerializer):
      user_id = serializers.PrimaryKeyRelatedField(source='user', queryset=User.objects.all())
      class Meta:
          model = DukeDSUser
          fields = ('id', 'user_id','url','dds_id', 'api_key', 'full_name', 'email')
subject: Remove StringRelatedField in favor of SlugRelatedFIeld