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from typing import List, Optional
from sqlmodel import Field, Relationship, Session, SQLModel, create_engine, select, text
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", passive_deletes="all")
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", ondelete="SET NULL"
)
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)
with engine.connect() as connection:
connection.execute(text("PRAGMA foreign_keys=ON")) # for SQLite only
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)
def delete_team():
with Session(engine) as session:
statement = select(Team).where(Team.name == "Wakaland")
team = session.exec(statement).one()
session.delete(team)
session.commit()
print("Deleted team:", team)
def select_deleted_heroes():
with Session(engine) as session:
statement = select(Hero).where(Hero.name == "Black Lion")
result = session.exec(statement)
hero = result.first()
print("Black Lion has no team:", hero)
statement = select(Hero).where(Hero.name == "Princess Sure-E")
result = session.exec(statement)
hero = result.first()
print("Princess Sure-E has no team:", hero)
def main():
create_db_and_tables()
create_heroes()
delete_team()
select_deleted_heroes()
if __name__ == "__main__":
main()
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