移除关系¶
现在假设 Spider-Boy 对 Rusty-Man 说：
我感觉不太好，Sharp先生
然后由于某些原因，他需要离开 Preventers 团队几年。😭
我们可以通过将关系设置为 None 来移除关系，和设置 team_id 一样，这也适用于新的关系属性 .team：
# 代码上面部分省略 👆
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
# 代码下面部分省略 👇
# 代码上面部分省略 👆
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
# 代码下面部分省略 👇
# 代码上面部分省略 👆
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
# 代码下面部分省略 👇
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
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="team")
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)
team_id: int | None = Field(default=None, foreign_key="team.id")
team: Team | None = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class Team(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="team")
class Hero(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
team: Optional[Team] = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class Team(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: List["Hero"] = Relationship(back_populates="team")
class Hero(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
team: Optional[Team] = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
当然，我们还需要记得将 update_heroes() 函数添加到 main() 中，以便在我们从命令行调用这个程序时运行：
# 代码上面部分省略 👆
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
# 代码下面部分省略 👇
# 代码上面部分省略 👆
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
# 代码下面部分省略 👇
# 代码上面部分省略 👆
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
# 代码下面部分省略 👇
👀 完整文件预览
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
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="team")
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)
team_id: int | None = Field(default=None, foreign_key="team.id")
team: Team | None = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class Team(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: list["Hero"] = Relationship(back_populates="team")
class Hero(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
team: Optional[Team] = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select
class Team(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
headquarters: str
heroes: List["Hero"] = Relationship(back_populates="team")
class Hero(SQLModel, table=True):
id: Optional[int] = Field(default=None, primary_key=True)
name: str = Field(index=True)
secret_name: str
age: Optional[int] = Field(default=None, index=True)
team_id: Optional[int] = Field(default=None, foreign_key="team.id")
team: Optional[Team] = Relationship(back_populates="heroes")
sqlite_file_name = "database.db"
sqlite_url = f"sqlite:///{sqlite_file_name}"
engine = create_engine(sqlite_url, echo=True)
def create_db_and_tables():
SQLModel.metadata.create_all(engine)
def create_heroes():
with Session(engine) as session:
team_preventers = Team(name="Preventers", headquarters="Sharp Tower")
team_z_force = Team(name="Z-Force", headquarters="Sister Margaret's Bar")
hero_deadpond = Hero(
name="Deadpond", secret_name="Dive Wilson", team=team_z_force
)
hero_rusty_man = Hero(
name="Rusty-Man", secret_name="Tommy Sharp", age=48, team=team_preventers
)
hero_spider_boy = Hero(name="Spider-Boy", secret_name="Pedro Parqueador")
session.add(hero_deadpond)
session.add(hero_rusty_man)
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_deadpond)
session.refresh(hero_rusty_man)
session.refresh(hero_spider_boy)
print("Created hero:", hero_deadpond)
print("Created hero:", hero_rusty_man)
print("Created hero:", hero_spider_boy)
hero_spider_boy.team = team_preventers
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Updated hero:", hero_spider_boy)
hero_black_lion = Hero(name="Black Lion", secret_name="Trevor Challa", age=35)
hero_sure_e = Hero(name="Princess Sure-E", secret_name="Sure-E")
team_wakaland = Team(
name="Wakaland",
headquarters="Wakaland Capital City",
heroes=[hero_black_lion, hero_sure_e],
)
session.add(team_wakaland)
session.commit()
session.refresh(team_wakaland)
print("Team Wakaland:", team_wakaland)
hero_tarantula = Hero(name="Tarantula", secret_name="Natalia Roman-on", age=32)
hero_dr_weird = Hero(name="Dr. Weird", secret_name="Steve Weird", age=36)
hero_cap = Hero(
name="Captain North America", secret_name="Esteban Rogelios", age=93
)
team_preventers.heroes.append(hero_tarantula)
team_preventers.heroes.append(hero_dr_weird)
team_preventers.heroes.append(hero_cap)
session.add(team_preventers)
session.commit()
session.refresh(hero_tarantula)
session.refresh(hero_dr_weird)
session.refresh(hero_cap)
print("Preventers new hero:", hero_tarantula)
print("Preventers new hero:", hero_dr_weird)
print("Preventers new hero:", hero_cap)
def select_heroes():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Preventers")
result = session.exec(statement)
team_preventers = result.one()
print("Preventers heroes:", team_preventers.heroes)
def update_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Spider-Boy")
result = session.exec(statement)
hero_spider_boy = result.one()
hero_spider_boy.team = None
session.add(hero_spider_boy)
session.commit()
session.refresh(hero_spider_boy)
print("Spider-Boy without team:", hero_spider_boy)
def main():
create_db_and_tables()
create_heroes()
select_heroes()
update_heroes()
if __name__ == "__main__":
main()
小结¶
这一章实在是太简短了，不是吗？🤔
无论如何，关系属性 使得处理存储在数据库中的关系变得既简单又直观。🎉