diff --git a/diner.py b/diner.py index cfd8ddfc6b3544a21d0943f0929090289db017d0..b229e2ac1aa0f269b7dca2566dd1da174ff9a6aa 100644 --- a/diner.py +++ b/diner.py @@ -26,21 +26,26 @@ class Item(Persisted): name = Column(String(256), nullable=False) price = Column(Integer, nullable=False) menu = relationship('Menu', back_populates='items') - orders = relationship('Order', uselist=True, secondary='order_items', back_populates='items') - # # # If there isn't any extra payload in the join table, there's no need to explicitly mention it + orders = relationship('Order', uselist=True, secondary='order_items', viewonly=True) + order_items = relationship('OrderItem', uselist=True, back_populates='item') + # # # If there is extra payload in the join table, then we need to make sure Item & Order can access it class Order(Persisted): __tablename__ = 'orders' order_id = Column(Integer, primary_key=True) timestamp = Column(DateTime) - items = relationship('Item', uselist=True, secondary='order_items', back_populates='orders') + items = relationship('Item', uselist=True, secondary='order_items', viewonly=True) + order_items = relationship('OrderItem', uselist=True, back_populates='order') class OrderItem(Persisted): __tablename__ = 'order_items' order_id = Column(Integer, ForeignKey('orders.order_id', ondelete='CASCADE'), primary_key=True) item_id = Column(Integer, ForeignKey('items.item_id', ondelete='CASCADE'), primary_key=True) + amount = Column(Integer) + item = relationship('Item', back_populates='order_items') + order = relationship('Order', back_populates='order_items') class DinerDatabase(object): diff --git a/diner_installer.py b/diner_installer.py index f397337c63e2b7bc6b88c77df36c9b1255ead8d2..f402880a9aaed56350ea6828306fecd4d9677a29 100644 --- a/diner_installer.py +++ b/diner_installer.py @@ -15,7 +15,7 @@ def add_starter_data(session): orange_juice = Item(menu=beverage_menu, name='Orange Juice', price=149) short_stack = Item(menu=food_menu, name='Pancakes', price=399) regular_pancakes = Item(menu=food_menu, name='Pancakes', price=499) - first_order = Order(items=[orange_juice]) + first_order = Order(order_items=[OrderItem(item=orange_juice, amount=2)]) session.add(beverage_menu) session.add(food_menu) session.add(orange_juice) @@ -41,6 +41,8 @@ def main(): print([item.name for item in the_order.items]) orange_juice: Item = session.query(Item).filter(Item.name == 'Orange Juice').one() print([order.order_id for order in orange_juice.orders]) + print([f'{order_item.amount} {order_item.item.name}s' for order_item in the_order.order_items]) + print([f'{order_item.amount} {orange_juice.name}s on order #{order_item.order.order_id}' for order_item in orange_juice.order_items]) except SQLAlchemyError as exception: print('Database setup failed!', file=stderr) print(f'Cause: {exception}', file=stderr)