import sqlalchemy
from sqlalchemy import Column
from sqlalchemy import ForeignKey
from sqlalchemy import Integer
from sqlalchemy import String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import attributes
from sqlalchemy.orm import relationship

Base = declarative_base()


class User(Base):
    __tablename__ = 'user'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    boston_addresses = relationship(
        "Address",
        # primaryjoin="and_(User.id==Address.user_id, Address.city=='Boston')",  # Not necessary but shows the use case
        viewonly=True)  # Setting viewonly = False prevents the issue


class Address(Base):
    __tablename__ = 'address'
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('user.id'))
    user = relationship('User', back_populates='boston_addresses')

    city = Column(String)


def main():
    session = setup_database_and_session()

    user = User()

    session.add(user)
    session.commit()

    # user.boston_addresses   # Reading the value here prevents the issue

    address = Address(user=user, city='Boston')
    
    actual = user.boston_addresses
    expected = [address]
    assert actual == expected, f"{actual} != {expected}"


def setup_database_and_session():
    engine = sqlalchemy.create_engine("sqlite://")
    session_maker = sqlalchemy.orm.sessionmaker(bind=engine)
    session = session_maker()
    Base.metadata.create_all(engine)
    return session


if __name__ == "__main__":
    main()