sqlalchemy仅在value不为None时应用筛选器

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

# 创建数据库连接
engine = create_engine('数据库连接字符串')

# 创建会话
Session = sessionmaker(bind=engine)
session = Session()

# 定义映射类
Base = declarative_base()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    age = Column(Integer)

# 应用筛选器
value = 'example'
query = session.query(User).filter(User.name == value)

# 执行查询
results = query.all()