old_contents: from crowdsourcing import models
  from rest_framework import serializers
  from crowdsourcing.serializers.dynamic import DynamicFieldsModelSerializer
  
  
  class RatingSerializer(DynamicFieldsModelSerializer):
      alias = serializers.ReadOnlyField()
      task_count = serializers.ReadOnlyField()
  
      class Meta:
          model = models.Rating
          fields = ('id', 'origin', 'target', 'weight',
                    'origin_type', 'alias', 'task_count', 'project')
          read_only_fields = ('origin',)
  
      def create(self, **kwargs):
          rating, created = models.Rating.objects \
              .update_or_create(origin=kwargs['origin'],
                                origin_type=self.validated_data['origin_type'],
                                target=self.validated_data['target'],
                                task=self.validated_data.get('task'),
                                defaults={'weight': self.validated_data['weight']})
          return rating
  
new_contents: from crowdsourcing import models
  from rest_framework import serializers
  from crowdsourcing.serializers.dynamic import DynamicFieldsModelSerializer
  
  
  class RatingSerializer(DynamicFieldsModelSerializer):
      alias = serializers.ReadOnlyField()
      task_count = serializers.ReadOnlyField()
  
      class Meta:
          model = models.Rating
          fields = ('id', 'origin', 'target', 'weight',
                    'origin_type', 'alias', 'task_count', 'task')
          read_only_fields = ('origin',)
  
      def create(self, **kwargs):
          rating, created = models.Rating.objects \
              .update_or_create(origin=kwargs['origin'],
                                origin_type=self.validated_data['origin_type'],
                                target=self.validated_data['target'],
                                task=self.validated_data.get('task'),
                                defaults={'weight': self.validated_data['weight']})
          return rating
  
subject: fix rating project -> task