From 9c17bb0bda0052a3f2e222cd7bb8b08ef1affde0 Mon Sep 17 00:00:00 2001
From: Christopher Bohn <bohn@unl.edu>
Date: Wed, 30 Mar 2022 08:45:39 -0500
Subject: [PATCH] added many-to-many without extra payload
---
diner.py | 6 +++++-
diner_installer.py | 22 +++++++++++++---------
2 files changed, 18 insertions(+), 10 deletions(-)
diff --git a/diner.py b/diner.py
index c0ad745..cfd8ddf 100644
--- a/diner.py
+++ b/diner.py
@@ -15,6 +15,7 @@ class Menu(Persisted):
__tablename__ = 'menus'
menu_id = Column(Integer, primary_key=True) # primary keys default to auto_increment
name = Column(String(256), nullable=False) # nullable is the default
+ items = relationship('Item', uselist=True, back_populates='menu')
class Item(Persisted):
@@ -24,19 +25,22 @@ class Item(Persisted):
menu_id = Column(Integer, ForeignKey('menus.menu_id', ondelete='CASCADE'), nullable=False)
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
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')
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)
class DinerDatabase(object):
diff --git a/diner_installer.py b/diner_installer.py
index cbca811..f397337 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(order_items=[OrderItem(item=orange_juice, amount=2)])
+ first_order = Order(items=[orange_juice])
session.add(beverage_menu)
session.add(food_menu)
session.add(orange_juice)
@@ -26,17 +26,21 @@ def add_starter_data(session):
def main():
try:
- url = DinerDatabase.construct_mysql_url('localhost', 3306, 'diner', 'root', 'cse1208')
+ url = DinerDatabase.construct_mysql_url('localhost', 33060, 'diner', 'root', 'cse1208')
diner_database = DinerDatabase(url)
diner_database.ensure_tables_exist()
print('Tables created.')
- # session = diner_database.create_session()
- # if already_has_data(session):
- # print('Not creating records because some already exist.')
- # else:
- # add_starter_data(session)
- # session.commit()
- # print('Records created.')
+ session = diner_database.create_session()
+ if already_has_data(session):
+ print('Not creating records because some already exist.')
+ else:
+ add_starter_data(session)
+ session.commit()
+ print('Records created.')
+ the_order: Order = session.query(Order).filter(Order.order_id == 1).one()
+ 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])
except SQLAlchemyError as exception:
print('Database setup failed!', file=stderr)
print(f'Cause: {exception}', file=stderr)
--
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