在SQLAlchemy查询过滤中使用变量

Question

可以在过滤器中使用变量吗？

我现在的代码是：

import sqlalchemy
from sqlalchemy import Table, MetaData, Column, Integer, String
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base


location = 'localhost'
engine_str = 'mysql+mysqlconnector://xxx:xxx@xxx/xxx'.format(location)
engine = sqlalchemy.create_engine(engine_str, echo=False)
session = sessionmaker(bind=engine)
connection = engine.connect()
session = session(bind=connection)
metadata = MetaData()
Base = declarative_base()

class Services(Base):
    """
    Service details on database
    """
    __tablename__ = 'some_table'
    id = Column(Integer, primary_key=True)
    color= Column(String)
    shape= Column(String)

    def __repr__(self):
        return self.shape

这个可以正常工作：

for c in session.query(Services).filter(Services.name.in_(['blue','red'])):
    print(c)

结果是：

    circle, square

但是使用变量时，返回的是：

services = ('blue','red')
for c in session.query(Services).filter(Services.name.in_([services])):
    print(c)

结果是：

mysql.connector.errors.ProgrammingError: Failed processing pyformat-parameters; 'MySQLConverter' object has no attribute '_tuple_to_mysql'

提前谢谢你们！

Answer 1

services已经是一个序列了，不需要再把它放进一个列表里：

for c in session.query(Services).filter(Services.name.in_(services)):