Python program: Retrieve user-specific orders with SQLAlchemy
Write a Python program to retrieve all orders for a specific user from the 'Order' table user using the SQLAlchemy model.
Sample Solution:
Code:
from sqlalchemy import create_engine, Column, Integer, Float, String, ForeignKey
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
# Create a SQLite database named shop.db
engine = create_engine('sqlite:///shop2.db', echo=False)
# Create a base class for declarative models
Base = declarative_base()
# Define the User model
class User(Base):
__tablename__ = 'users'
user_id = Column(Integer, primary_key=True)
user_name = Column(String, nullable=False)
user_email = Column(String, nullable=False)
# Define the Item model
class Item(Base):
__tablename__ = 'items'
item_id = Column(Integer, primary_key=True)
item_name = Column(String, nullable=False)
item_price = Column(Float, nullable=False)
item_quantity = Column(Integer, nullable=False)
orders = relationship("Order", back_populates="item") # Define the relationship to Order
# Define the Order model
class Order(Base):
__tablename__ = 'orders'
order_id = Column(Integer, primary_key=True)
user_id = Column(Integer, ForeignKey('users.user_id'), nullable=False)
item_id = Column(Integer, ForeignKey('items.item_id'), nullable=False)
order_quantity = Column(Integer, nullable=False)
item = relationship("Item", back_populates="orders") # Define the relationship to Item
# Create a session to interact with the database
Session = sessionmaker(bind=engine)
session = Session()
def get_orders_for_user(user_id):
orders = session.query(Order).filter_by(user_id=user_id).all()
return orders
# Retrieve and display all orders for a specific user
user_id = 1 # Replace with the user's ID
orders = get_orders_for_user(user_id)
print(f"Orders for user {user_id}:")
for order in orders:
print(f"Order ID: {order.order_id}, Item ID: {order.item_id}, Quantity: {order.order_quantity}")
# Close the session
session.close()
Output:
Orders for user 1: Order ID: 100, Item ID: 1, Quantity: 2 Order ID: 101, Item ID: 3, Quantity: 10 Order ID: 103, Item ID: 1, Quantity: 3
Flowchart:
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Next: Calculate total order cost with SQLAlchemy.
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