Relationships & Nested Resources: One-to-Many with SQLAlchemy

Modeling Real-World Complexity Real data has relationships. A phone belongs to Electronics. A keyboard belongs to Accessories. Flat data doesn't capture this relationships do. The One-to-Many Relationship One Category has many Items. One Item belongs to one Category. class Category(Base): __tablename__ = "categories" id = Column(Integer, primary_key=True) name = Column(String, unique=True, nullable=False) items = relationship("Item", back_populates="category") class Item(Base): __tablename__ = "items" id = Column(Integer, primary_key=True) name = Column(String, nullable=False) price = Column(Numeric(10, 2), nullable=False) category_id = Column(Integer, ForeignKey("categories.id")) category = relationship("Category", back_populates="items") The ForeignKey links items to categories. The relationship() tells SQLAlchemy how to navigate between them. Nested JSON Response GET /items/1 returns: { "id": 1, "name": "Laptop", "price": 999.99, "category": { "id": 1, "name": "Electronics", "descri