SQLModel 错误："AttributeError: 'Team' object has no attribute 'heroes'"

Question

我正在尝试使用Tiangolo的SQLModel，我尝试了这个文档中的示例代码:https://sqlmodel.tiangolo.com/tutorial/relationship-attributes/read-relationships/

代码如下:

from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select

class Team(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: List["Hero"] = Relationship(back_populates="team")

class Hero(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
team: Optional[Team] = Relationship(back_populates="heroes")

sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)

def create_db_and_tables():
SQLModel.metadata.create_all(engine)

def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret’s Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)

def select_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
statement = select(Team).where(Team.id == hero_spider_boy.id)
result = session.exec(statement)
team = result.first()
print("Spider-Boy's team:", team)
print("Spider-Boy's team again:", hero_spider_boy.team)

def main():
create_db_and_tables()
create_heroes()
select_heroes()

if __name__ == "__main__":
main()

但是，当我尝试运行它时，我得到了以下错误:

File "example.py", line 83, in create_heroes
team_preventers.heroes.append(hero_tarantula)
AttributeError: 'Team' object has no attribute 'heroes'

我不明白为什么会发生这个错误，因为heroes属性似乎在Team类中定义得很好。我很确定教程中的示例代码不会出错。我错过什么了吗?谢谢!

注意:在Python 3.9上使用最新的0.0.6 sqlmodel版本

Answer 1

SQLModel有一个突出的SQLAlchemy 1.4.36+问题

https://github.com/tiangolo/sqlmodel/issues/315

,

pip install sqlalchemy==1.4.35