更新和删除多对多关系¶
现在我们将了解如何更新和删除这些多对多关系。
我们将从上次代码中断的地方继续。
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine
class HeroTeamLink(SQLModel, table=True):
team_id: int | None = Field(default=None, foreign_key="team.id", primary_key=True)
hero_id: int | None = Field(default=None, foreign_key="hero.id", primary_key=True)
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="teams", link_model=HeroTeamLink)
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
if __name__ == "__main__":
main()
🤓 其他版本和变体
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: List[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
if __name__ == "__main__":
main()
获取要更新的数据¶
现在我们来创建一个函数update_heroes()。
我们将获取蜘蛛男孩和Z-Force团队。
由于您已经知道这些是如何进行的，我将使用短版本并在一个Python语句中获取数据。
因为我们现在使用select()，所以我们也必须导入它。
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
# Code here omitted 👈
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
# Code below omitted 👇
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: int | None = Field(default=None, foreign_key="team.id", primary_key=True)
hero_id: int | None = Field(default=None, foreign_key="hero.id", primary_key=True)
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="teams", link_model=HeroTeamLink)
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
🤓 其他版本和变体
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: List[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
当然，我们必须将update_heroes()添加到我们的main()函数中。
# Code above omitted 👆
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: int | None = Field(default=None, foreign_key="team.id", primary_key=True)
hero_id: int | None = Field(default=None, foreign_key="hero.id", primary_key=True)
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="teams", link_model=HeroTeamLink)
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
🤓 其他版本和变体
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: List[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
添加多对多关系¶
现在我们假设蜘蛛男孩认为Z-Force团队非常酷，并决定加入他们。
我们可以使用相同的关系属性将hero_spider_boy包含在team_z_force.heroes中。
# Code above omitted 👆
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
# Code below omitted 👇
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: int | None = Field(default=None, foreign_key="team.id", primary_key=True)
hero_id: int | None = Field(default=None, foreign_key="hero.id", primary_key=True)
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="teams", link_model=HeroTeamLink)
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
🤓 其他版本和变体
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: List[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
提示
因为我们在提交后立即访问模型中的属性，即hero_spider_boy.teams和team_z_force.heroes，数据会自动刷新。
因此我们不必调用session.refresh()。
然后我们提交更改，刷新，并打印更新后的蜘蛛男孩的英雄们以确认。
请注意，我们只将Z-Force添加到会话中，然后提交。
我们从未将蜘蛛男孩添加到会话中，甚至从未刷新过他。但我们仍然打印他的团队。
这仍然有效，因为我们在模型中的Relationship()中使用了back_populates。这样，SQLModel（实际上是SQLAlchemy）可以跟踪更改和更新，并确保它们也发生在其他相关模型的关系上。🎉
运行程序¶
您可以通过在命令行中运行程序来确认一切正常
$ python app.py
// Previous output omitted 🙈
// Create the new many-to-many relationship
INFO Engine INSERT INTO heroteamlink (team_id, hero_id) VALUES (?, ?)
INFO Engine [generated in 0.00020s] (1, 3)
INFO Engine COMMIT
// Start a new automatic transaction
INFO Engine BEGIN (implicit)
// Automatically refresh the data while accessing the attribute .teams
INFO Engine SELECT hero.id AS hero_id, hero.name AS hero_name, hero.secret_name AS hero_secret_name, hero.age AS hero_age
FROM hero
WHERE hero.id = ?
INFO Engine [generated in 0.00044s] (3,)
INFO Engine SELECT team.id AS team_id, team.name AS team_name, team.headquarters AS team_headquarters
FROM team, heroteamlink
WHERE ? = heroteamlink.hero_id AND team.id = heroteamlink.team_id
INFO Engine [cached since 0.1648s ago] (3,)
// Print Spider-Boy teams, including Z-Force 🎉
Updated Spider-Boy's Teams: [
Team(id=2, name='Preventers', headquarters='Sharp Tower'),
Team(id=1, name='Z-Force', headquarters='Sister Margaret's Bar')
]
// Automatically refresh the data while accessing the attribute .heores
INFO Engine SELECT hero.id AS hero_id, hero.name AS hero_name, hero.secret_name AS hero_secret_name, hero.age AS hero_age
FROM hero, heroteamlink
WHERE ? = heroteamlink.team_id AND hero.id = heroteamlink.hero_id
INFO Engine [cached since 0.1499s ago] (1,)
// Print Z-Force heroes, including Spider-Boy 🎉
Z-Force heroes: [
Hero(name='Deadpond', age=None, id=1, secret_name='Dive Wilson'),
Hero(name='Spider-Boy', age=None, id=3, secret_name='Pedro Parqueador', teams=[
Team(id=2, name='Preventers', headquarters='Sharp Tower'),
Team(id=1, name='Z-Force', headquarters='Sister Margaret's Bar', heroes=[...])
])
]
删除多对多关系¶
现在假设在加入团队后，蜘蛛男孩意识到他们的“生命保障政策”比他习惯的要宽松得多。💀
而且他们的职业安全与健康也没有那么好...💥
所以，蜘蛛男孩决定离开Z-Force。
让我们更新关系以从hero_spider_boy.teams中移除team_z_force。
因为hero_spider_boy.teams只是一个列表（一个由SQLAlchemy管理的特殊列表，但仍然是一个列表），我们可以使用标准的列表方法。
在这种情况下，我们使用.remove()方法，它接受一个项目并将其从列表中删除。
# Code above omitted 👆
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
# Code below omitted 👇
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: int | None = Field(default=None, foreign_key="team.id", primary_key=True)
hero_id: int | None = Field(default=None, foreign_key="hero.id", primary_key=True)
class Team(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="teams", link_model=HeroTeamLink)
class Hero(SQLModel, table=True):
id: int | None = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: int | None = Field(default=None, index=True)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
🤓 其他版本和变体
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: list[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class HeroTeamLink(SQLModel, table=True):
team_id: Optional[int] = Field(
default=None, foreign_key="team.id", primary_key=True
)
hero_id: Optional[int] = Field(
default=None, foreign_key="hero.id", primary_key=True
)
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="teams", link_model=HeroTeamLink)
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)
teams: List[Team] = Relationship(back_populates="heroes", link_model=HeroTeamLink)
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",
teams=[team_z_force, team_preventers],
)
hero_rusty_man = Hero(
name="Rusty-Man",
secret_name="Tommy Sharp",
age=48,
teams=[team_preventers],
)
hero_spider_boy = Hero(
name="Spider-Boy", secret_name="Pedro Parqueador", teams=[team_preventers]
)
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("Deadpond:", hero_deadpond)
print("Deadpond teams:", hero_deadpond.teams)
print("Rusty-Man:", hero_rusty_man)
print("Rusty-Man Teams:", hero_rusty_man.teams)
print("Spider-Boy:", hero_spider_boy)
print("Spider-Boy Teams:", hero_spider_boy.teams)
def update_heroes():
with Session(engine) as session:
hero_spider_boy = session.exec(
select(Hero).where(Hero.name == "Spider-Boy")
).one()
team_z_force = session.exec(select(Team).where(Team.name == "Z-Force")).one()
team_z_force.heroes.append(hero_spider_boy)
session.add(team_z_force)
session.commit()
print("Updated Spider-Boy's Teams:", hero_spider_boy.teams)
print("Z-Force heroes:", team_z_force.heroes)
hero_spider_boy.teams.remove(team_z_force)
session.add(team_z_force)
session.commit()
print("Reverted Z-Force's heroes:", team_z_force.heroes)
print("Reverted Spider-Boy's teams:", hero_spider_boy.teams)
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
这一次，只是为了再次展示，通过使用back_populates，SQLModel（实际上是SQLAlchemy）会负责通过它们的关系连接模型，即使我们是从hero_spider_boy对象执行操作（修改hero_spider_boy.teams），我们还是将team_z_force添加到了会话中。然后我们提交了它，甚至没有添加hero_spider_boy。
这仍然有效，因为更新hero_spider_boy中的团队，由于它们与back_populates同步，更改也会反映在team_z_force中，所以它也有要保存到数据库的更改（蜘蛛男孩被移除了）。
然后我们添加团队，并提交更改，这会更新team_z_force对象，并且因为它更改了也与hero_spider_boy有连接的表，所以它在内部也被标记为已更新，因此一切正常。
然后我们再次打印它们以确认一切正常。
再次运行程序¶
要确认这最后一部分是否有效，您可以再次运行程序，它将输出类似以下内容
$ python app.py
// Previous output omitted 🙈
// Delete the row in the link table
INFO Engine DELETE FROM heroteamlink WHERE heroteamlink.team_id = ? AND heroteamlink.hero_id = ?
INFO Engine [generated in 0.00043s] (1, 3)
// Save the changes
INFO Engine COMMIT
// Automatically start a new transaction
INFO Engine BEGIN (implicit)
// Automatically refresh the data while accessing the attribute .heroes
INFO Engine SELECT team.id AS team_id, team.name AS team_name, team.headquarters AS team_headquarters
FROM team
WHERE team.id = ?
INFO Engine [generated in 0.00029s] (1,)
INFO Engine SELECT hero.id AS hero_id, hero.name AS hero_name, hero.secret_name AS hero_secret_name, hero.age AS hero_age
FROM hero, heroteamlink
WHERE ? = heroteamlink.team_id AND hero.id = heroteamlink.hero_id
INFO Engine [cached since 0.5625s ago] (1,)
// Print the Z-Force heroes after reverting the changes
Reverted Z-Force's heroes: [
Hero(name='Deadpond', age=None, id=1, secret_name='Dive Wilson')
]
// Automatically refresh the data while accessing the attribute .teams
INFO Engine SELECT hero.id AS hero_id, hero.name AS hero_name, hero.secret_name AS hero_secret_name, hero.age AS hero_age
FROM hero
WHERE hero.id = ?
INFO Engine [cached since 0.4209s ago] (3,)
INFO Engine SELECT team.id AS team_id, team.name AS team_name, team.headquarters AS team_headquarters
FROM team, heroteamlink
WHERE ? = heroteamlink.hero_id AND team.id = heroteamlink.team_id
INFO Engine [cached since 0.5842s ago] (3,)
// Print Spider-Boy's teams after reverting the changes
Reverted Spider-Boy's teams: [
Team(id=2, name='Preventers', headquarters='Sharp Tower')
]
// Automatically roll back any possible previously unsaved transaction
INFO Engine ROLLBACK
回顾¶
在设置了链接模型和关系属性之后，更新和删除多对多关系非常简单。
您可以只使用常见的列表操作。🚀