✨ Add source examples for docs

docs_src/tutorial/many_to_many/tutorial003.py

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+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
+    )
+    is_training: bool = False
+
+    team: "Team" = Relationship(back_populates="hero_links")
+    hero: "Hero" = Relationship(back_populates="team_links")
+
+
+class Team(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    name: str
+    headquarters: str
+
+    hero_links: List[HeroTeamLink] = Relationship(back_populates="team")
+
+
+class Hero(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    name: str
+    secret_name: str
+    age: Optional[int] = None
+
+    team_links: List[HeroTeamLink] = Relationship(back_populates="hero")
+
+
+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",
+        )
+        hero_rusty_man = Hero(
+            name="Rusty-Man",
+            secret_name="Tommy Sharp",
+            age=48,
+        )
+        hero_spider_boy = Hero(
+            name="Spider-Boy",
+            secret_name="Pedro Parqueador",
+        )
+        deadpond_team_z_link = HeroTeamLink(team=team_z_force, hero=hero_deadpond)
+        deadpond_preventers_link = HeroTeamLink(
+            team=team_preventers, hero=hero_deadpond, is_training=True
+        )
+        spider_boy_preventers_link = HeroTeamLink(
+            team=team_preventers, hero=hero_spider_boy, is_training=True
+        )
+        rusty_man_preventers_link = HeroTeamLink(
+            team=team_preventers, hero=hero_rusty_man
+        )
+
+        session.add(deadpond_team_z_link)
+        session.add(deadpond_preventers_link)
+        session.add(spider_boy_preventers_link)
+        session.add(rusty_man_preventers_link)
+        session.commit()
+
+        for link in team_z_force.hero_links:
+            print("Z-Force hero:", link.hero, "is training:", link.is_training)
+
+        for link in team_preventers.hero_links:
+            print("Preventers hero:", link.hero, "is training:", link.is_training)
+
+
+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()
+
+        spider_boy_z_force_link = HeroTeamLink(
+            team=team_z_force, hero=hero_spider_boy, is_training=True
+        )
+        team_z_force.hero_links.append(spider_boy_z_force_link)
+        session.add(team_z_force)
+        session.commit()
+
+        print("Updated Spider-Boy's Teams:", hero_spider_boy.team_links)
+        print("Z-Force heroes:", team_z_force.hero_links)
+
+        for link in hero_spider_boy.team_links:
+            if link.team.name == "Preventers":
+                link.is_training = False
+
+        session.add(hero_spider_boy)
+        session.commit()
+
+        for link in hero_spider_boy.team_links:
+            print("Spider-Boy team:", link.team, "is training:", link.is_training)
+
+
+def main():
+    create_db_and_tables()
+    create_heroes()
+    update_heroes()
+
+
+if __name__ == "__main__":
+    main()