如何通过sqlalchemy在Postgresql中记录时间

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

engine = create_engine('postgresql://username:password@localhost/database_name')
Session = sessionmaker(bind=engine)
session = Session()

Base = declarative_base()

class MyModel(Base):
    __tablename__ = 'my_table'
    id = Column(Integer, primary_key=True)
    created_at = Column(DateTime, default=datetime.utcnow)

Base.metadata.create_all(engine)

new_record = MyModel()
session.add(new_record)
session.commit()

records = session.query(MyModel).all()
for record in records:
    print(record.created_at)