Sqlalchemy -如何生成仅返回jsonb列中字段的查询

from sqlalchemy import create_engine, select
from sqlalchemy.orm import sessionmaker
from sqlalchemy.dialects.postgresql import JSONB

engine = create_engine('postgresql://username:password@host:port/database')

Session = sessionmaker(bind=engine)
session = Session()

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column

Base = declarative_base()

class MyTable(Base):
    __tablename__ = 'my_table'
    id = Column(Integer, primary_key=True)
    data = Column(JSONB)

result = session.query(MyTable.data['field1'], MyTable.data['field2']).all()

import json

json_result = json.dumps(result)