old_contents: from core.models.post_boot import BootScript
  from rest_framework import serializers
  
  
  class BootScriptSerializer(serializers.ModelSerializer):
      created_by = serializers.SlugRelatedField(slug_field='username')
      script_type = serializers.SlugRelatedField(slug_field='name')
      class Meta:
          model = BootScript
          exclude = ('instances', 'applications',)
new_contents: from core.models.post_boot import BootScript, ScriptType
  from core.models.user import AtmosphereUser
  from rest_framework import serializers
  
  
  class BootScriptSerializer(serializers.ModelSerializer):
      created_by = serializers.SlugRelatedField(slug_field='username', queryset=AtmosphereUser.objects.all())
      script_type = serializers.SlugRelatedField(slug_field='name', queryset=ScriptType.objects.all())
  
      class Meta:
          model = BootScript
          exclude = ('instances', 'applications',)
subject: upgrade BootScriptSerializer to DRF3