使用sqlalchemy.sql.functions.char_length作为过滤条件

from sqlalchemy import create_engine, Column, String, Integer, text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.sql.functions import char_length

Base = declarative_base()

class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String)

engine = create_engine('sqlite:///users.db')
Base.metadata.create_all(engine)

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

# 添加一些用户数据
session.add_all([
    User(name='John'),
    User(name='Jane'),
    User(name='Jack'),
    User(name='Jill')
])
session.commit()

# 使用char_length作为过滤条件
result = session.query(User).filter(char_length(User.name) == 4).all()
print(result)