class Type(Base):
    __tablename__ = 'Type'
    id = Column(Integer, primary_key=True)
    name = Column(String, unique = True)
    def __init__(self, name):
        self.name = name

type1 = Type('name1')
session.add(type1)
type2 = Type(type1.name)
session.add(type2)

Type.__table__.create(engine)

try:
  existing = session.query(Type).filter_by(name='name1').one()
  # do something with existing
except:
  newobj = Type('name1')
  session.add(newobj)

try:
  existing = session.query(Type).filter_by(name='name1').one()
# do something with existing
except NoResultFound:
  newobj = Type('name1')
  session.add(newobj)