Update and Remove Many-to-Many Relationships¶
Jetzt sehen wir, wie diese Many-to-Many-Beziehungen aktualisiert und entfernt werden.
Wir machen dort weiter, wo wir mit dem vorherigen Code aufgehört haben.
👀 Vorschau der vollständigen Datei
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()
🤓 Andere Versionen und Varianten
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()
Get Data to Update¶
Erstellen wir nun eine Funktion update_heroes().
Wir holen uns Spider-Boy und das Team Z-Force.
Da Sie bereits wissen, wie das geht, verwende ich die Kurzfassung und rufe die Daten in einer einzigen Python-Anweisung ab.
Und da wir jetzt select() verwenden, müssen wir es auch importieren.
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 👇
👀 Vorschau der vollständigen Datei
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()
🤓 Andere Versionen und Varianten
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()
Und natürlich müssen wir update_heroes() zu unserer main()-Funktion hinzufügen
# Code above omitted 👆
def main():
create_db_and_tables()
create_heroes()
update_heroes()
if __name__ == "__main__":
main()
👀 Vorschau der vollständigen Datei
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()
🤓 Andere Versionen und Varianten
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()
Add Many-to-Many Relationships¶
Stellen wir uns nun vor, dass Spider-Boy das Team Z-Force super cool findet und beschließt, dorthin zu gehen und sich ihnen anzuschließen.
Wir können dieselben Beziehungsattribute verwenden, um hero_spider_boy in die team_z_force.heroes aufzunehmen.
# 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 👇
👀 Vorschau der vollständigen Datei
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()
🤓 Andere Versionen und Varianten
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()
Tipp
Da wir direkt nach dem Commit auf ein Attribut in den Modellen zugreifen, mit hero_spider_boy.teams und team_z_force.heroes, werden die Daten automatisch aktualisiert.
Wir müssen also session.refresh() nicht aufrufen.
Anschließend committen wir die Änderung, aktualisieren und geben die aktualisierten Helden von Spider-Boy aus, um dies zu bestätigen.
Beachten Sie, dass wir nur Z-Force zur Session adden, dann committen.
Wir fügen Spider-Boy niemals zur Session hinzu und aktualisieren ihn nie. Aber wir geben trotzdem seine Teams aus.
Das funktioniert immer noch korrekt, da wir back_populates im Relationship() in den Modellen verwenden. Auf diese Weise kann SQLModel (eigentlich SQLAlchemy) die Änderungen und Aktualisierungen verfolgen und sicherstellen, dass sie auch in den Beziehungen der anderen verknüpften Modelle stattfinden. 🎉
Das Programm ausführen¶
Sie können bestätigen, dass alles funktioniert, indem Sie das Programm in der Kommandozeile ausführen
$ 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=[...])
])
]
Remove Many-to-Many Relationships¶
Nehmen wir nun an, dass Spider-Boy direkt nach dem Beitritt zum Team feststellt, dass die "Lebenserhaltungsrichtlinien" viel lockerer sind, als er es gewohnt ist. 💀
Und ihre *Arbeitssicherheit und Gesundheitsschutz* ist auch nicht gerade berauschend... 💥
Also beschließt Spider-Boy, Z-Force zu verlassen.
Aktualisieren wir die Beziehungen, um team_z_force aus hero_spider_boy.teams zu entfernen.
Da hero_spider_boy.teams nur eine Liste ist (eine spezielle Liste, die von SQLAlchemy verwaltet wird, aber eine Liste), können wir die Standardlistenmethoden verwenden.
In diesem Fall verwenden wir die Methode .remove(), die ein Element nimmt und es aus der Liste entfernt.
# 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 👇
👀 Vorschau der vollständigen Datei
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()
🤓 Andere Versionen und Varianten
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()
Und dieses Mal, nur um erneut zu zeigen, dass durch die Verwendung von back_populates SQLModel (eigentlich SQLAlchemy) die Verbindung der Modelle über ihre Beziehungen kümmert, auch wenn wir die Operation vom hero_spider_boy-Objekt aus durchgeführt haben (indem wir hero_spider_boy.teams geändert haben), fügen wir team_z_force zur Session hinzu. Und wir committen das, ohne hero_spider_boy überhaupt hinzuzufügen.
Dies funktioniert immer noch, da durch die Aktualisierung der Teams in hero_spider_boy, da diese mit back_populates synchronisiert sind, die Änderungen auch in team_z_force widergespiegelt werden, sodass es auch Änderungen zum Speichern in der DB gibt (dass Spider-Boy entfernt wurde).
Und dann fügen wir das Team hinzu und committen die Änderungen, was das team_z_force-Objekt aktualisiert, und da es die Tabelle geändert hat, die auch eine Verbindung mit hero_spider_boy hatte, wird es intern auch als aktualisiert markiert, so dass alles funktioniert.
Und dann geben wir sie einfach noch einmal aus, um zu bestätigen, dass alles korrekt funktioniert hat.
Run the Program Again¶
Um zu bestätigen, dass dieser letzte Teil funktioniert hat, können Sie das Programm erneut ausführen. Es wird etwa Folgendes ausgeben:
$ 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
Zusammenfassung¶
Das Aktualisieren und Entfernen von Many-to-Many-Beziehungen ist nach der Einrichtung des Link-Modells und der Beziehungsattribute recht einfach.
Sie können einfach gängige Listenoperationen verwenden. 🚀