from sqlalchemy import Column, DateTime, String, create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import scoped_session, sessionmaker

Base = declarative_base()


class Pet(Base):
    __tablename__ = 'pets'
    id = Column(String(20), primary_key=True)
    name = Column(String(100))
    animal_type = Column(String(20))
    created = Column(DateTime())
    
    def update(self, id=None, name=None, animal_type=None, tags=None, 
            created=None):
        if name is not None:
            self.name = name
        if animal_type is not None:
            self.animal_type = animal_type
        if created is not None:
            self.created = created
        
    def dump(self):
        return dict([(k,v) for k,v in vars(self).items() 
                if not k.startswith('_')])


def init_db(uri):
    engine = create_engine(uri, convert_unicode=True)
    db_session = scoped_session(sessionmaker(autocommit=False, autoflush=False,
            bind=engine))
    Base.query = db_session.query_property()
    Base.metadata.create_all(bind=engine)
    return db_session