✨ Add (module): SQLAlchemy ORM example

Author: jpcadena

introduction/sa_orm.py

@@ -0,0 +1,129 @@
+"""
+This module demonstrates the use of SQLAlchemy as a full Object Relational
+ Mapper (ORM) for interacting with a SQL database. It defines classes
+  representing database tables and includes functionality to add players to
+   teams, leveraging the ORM capabilities for database operations.
+"""
+
+from typing import Optional, Type
+
+from sqlalchemy import (
+    Column,
+    Engine,
+    ForeignKey,
+    Integer,
+    String,
+    create_engine,
+)
+from sqlalchemy.orm import (
+    DeclarativeBase,
+    declarative_base,
+    relationship,
+    sessionmaker,
+)
+
+Base: Type[DeclarativeBase] = declarative_base()
+url: str = "mssql+pyodbc://user:[email protected]"
+engine: Engine = create_engine(
+    url,
+    pool_pre_ping=True,
+    future=True,
+    echo=True,
+)
+Session = sessionmaker(
+    bind=engine,
+)
+session = Session()
+
+
+class Team(Base):  # type: ignore
+    """
+    Represents a team in the database with its name and list of players.
+    """
+
+    __tablename__ = "teams"
+
+    id = Column(
+        Integer,
+        primary_key=True,
+    )
+    name = Column(
+        String,
+    )
+    players = relationship(
+        "Player",
+        backref="team",
+    )
+
+
+class Player(Base):  # type: ignore
+    """
+    Represents a player in the database with the name of the player and the
+    jersey.
+    """
+
+    __tablename__ = "players"
+
+    id = Column(
+        Integer,
+        primary_key=True,
+    )
+    name = Column(
+        String,
+    )
+    number = Column(
+        Integer,
+    )
+    team_id = Column(
+        Integer,
+        ForeignKey("teams.id"),
+    )
+
+
+Base.metadata.create_all(
+    engine,
+)
+
+
+def add_player_to_team(
+    player_name: str,
+    player_number: int,
+    team_name: str,
+) -> None:
+    """
+    Adds a player to a team in the database, creating the team if it does not
+     exist.
+    :param player_name: Name of the player to be added.
+    :type player_name: str
+    :param player_number: Jersey number of the player.
+    :type player_number: int
+    :param team_name: Name of the team to which the player will be added.
+    :type team_name: str
+    :return: None
+    :rtype: NoneType
+    """
+    team: Optional[Type[Team]] | Team = (
+        session.query(Team).filter_by(name=team_name).first()
+    )
+    if not team:
+        team = Team(
+            name=team_name,
+        )
+        session.add(team)
+        session.commit()
+    new_player = Player(
+        team.id,
+        player_name,
+        player_number,
+    )
+    session.add(new_player)
+    session.commit()
+
+
+add_player_to_team(
+    "Juan Carlos",
+    9,
+    "FC Pythonistas",
+)
+if fcp_team := (session.query(Team).filter_by(name="FC Pythonistas").first()):
+    print(f"Team: {fcp_team.name}")