old_contents: from sqlalchemy_utils import UUIDType
  
  from zou.app import db
  from zou.app.models.serializer import SerializerMixin
  from zou.app.models.base import BaseMixin
  
  
  class News(db.Model, BaseMixin, SerializerMixin):
      """
      A notification is stored each time a comment is posted.
      """
  
      change = db.Column(db.Boolean, nullable=False, default=False)
      author_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("person.id"),
          nullable=False,
          index=True,
      )
      comment_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("comment.id"),
          nullable=True,
          index=True,
      )
      task_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("task.id"),
          nullable=False,
          index=True,
      )
      preview_file_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("preview_file.id"),
          nullable=True,
          index=True,
      )
  
      @classmethod
      def create_from_import(cls, data):
          data = {
              "id": data["id"],
              "updated_at": data["created_at"],
              "created_at": data["created_at"],
              "change": data["change"],
              "author_id": data["author_id"],
              "comment_id": data["comment_id"],
              "preview_file_id": data["preview_file_id"],
              "task_id": data["task_id"],
          }
          previous_data = cls.get(data["id"])
          if previous_data is None:
              return (cls.create(**data), True)
          else:
              previous_data.update(data)
              return (previous_data, False)
  
new_contents: from sqlalchemy_utils import UUIDType
  
  from zou.app import db
  from zou.app.models.serializer import SerializerMixin
  from zou.app.models.base import BaseMixin
  
  
  class News(db.Model, BaseMixin, SerializerMixin):
      """
      A news is created each time a comment is posted.
      """
  
      change = db.Column(db.Boolean, nullable=False, default=False)
      author_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("person.id"),
          nullable=False,
          index=True,
      )
      comment_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("comment.id"),
          nullable=True,
          index=True,
      )
      task_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("task.id"),
          nullable=False,
          index=True,
      )
      preview_file_id = db.Column(
          UUIDType(binary=False),
          db.ForeignKey("preview_file.id"),
          nullable=True,
          index=True,
      )
  
      @classmethod
      def create_from_import(cls, data):
          data = {
              "id": data["id"],
              "updated_at": data["created_at"],
              "created_at": data["created_at"],
              "change": data["change"],
              "author_id": data["author_id"],
              "comment_id": data["comment_id"],
              "preview_file_id": data["preview_file_id"],
              "task_id": data["task_id"],
          }
          previous_data = cls.get(data["id"])
          if previous_data is None:
              return (cls.create(**data), True)
          else:
              previous_data.update(data)
              return (previous_data, False)
  
subject: Fix typo in the news model description