old_contents: import sys
  
  from sqlalchemy import create_engine
  from sqlalchemy import func
  from sqlalchemy import Column
  from sqlalchemy import Date
  from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy import String
  from sqlalchemy import Text
  from sqlalchemy import UniqueConstraint
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  TablePrefix = 'ACT_'
  DatabaseEngineURL = 'postgresql:///vagrant'
  
  Base = declarative_base()
  
  class Category(Base):
      __tablename__ = '%s%s' % (TablePrefix, 'Category')
  
      id = Column(Integer, primary_key=True)
      label = Column(String(127), nullable=False, unique=True)
  
      @property
      def serialize(self):
          # Returns object data in a serializable format
          return {
                 'id': self.id,
              'label': self.label
          }
  
  class Item(Base):
      __tablename__ = '%s%s' % (TablePrefix,'Item')
  
      id = Column(Integer, primary_key=True)
      label = Column(String(127), nullable=False)
      date = Column(Date, default=func.now())
  
      category_id = Column(Integer, ForeignKey(Category.id), nullable=False)
      category = relationship(Category)
  
      UniqueConstraint('category_id', 'label')
  
      @property
      def serialize(self):
          # Returns object data in a serializable format
          return {
                       'id': self.id,
                    'label': self.label,
                     'date': self.date,
              'category_id': self.category_id
          }
  
  # declare and create database engine
  engine = create_engine(DatabaseEngineURL)
  Base.metadata.create_all(engine)
  
new_contents: import sys
  
  from sqlalchemy import create_engine
  from sqlalchemy import func
  from sqlalchemy import Column
  from sqlalchemy import Date
  from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy import String
  from sqlalchemy import Text
  from sqlalchemy import UniqueConstraint
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  
  TablePrefix = 'ACT_'
  DatabaseEngineURL = 'postgresql:///vagrant'
  
  Base = declarative_base()
  
  class Category(Base):
      __tablename__ = '%s%s' % (TablePrefix, 'Category')
  
      id = Column(Integer, primary_key=True)
      label = Column(String(127), nullable=False, unique=True)
  
      @property
      def serialize(self):
          # Returns object data in a serializable format
          return {
                 'id': self.id,
              'label': self.label
          }
  
  class Item(Base):
      __tablename__ = '%s%s' % (TablePrefix,'Item')
  
      id = Column(Integer, primary_key=True)
      label = Column(String(127), nullable=False)
      date = Column(Date, default=func.now())
      description = Column(String)
  
      category_id = Column(Integer, ForeignKey(Category.id), nullable=False)
      category = relationship(Category)
  
      UniqueConstraint('category_id', 'label')
  
      @property
      def serialize(self):
          # Returns object data in a serializable format
          return {
                       'id': self.id,
                    'label': self.label,
                     'date': self.date,
              'description': self.description,
              'category_id': self.category_id
          }
  
  # declare and create database engine
  engine = create_engine(DatabaseEngineURL)
  Base.metadata.create_all(engine)
  
subject: add description column to item object