Shopping Carts

const carts = container('carts', {
  id: field.string(),
  userId: field.string(),
  items: field.array(field.object({
    productId: field.string(),
    quantity: field.number(),
    price: field.number()
  })),
  total: field.number(),
  updatedAt: field.date(),
  ttl: field.number() // Expire abandoned carts
}).partitionKey('userId');

async function addToCart(userId: string, item: CartItem) {
  const cart = await db.carts.findUnique({
    where: { id: userId, userId }
  });
  
  if (!cart) {
    return await db.carts.create({
      data: {
        id: userId,
        userId,
        items: [item],
        total: item.price * item.quantity,
        updatedAt: new Date(),
        ttl: 7 * 24 * 60 * 60 // Expire after 7 days
      }
    });
  }
  
  // Update existing cart
  const newItems = [...cart.items, item];
  const newTotal = newItems.reduce((sum, i) => sum + i.price * i.quantity, 0);
  
  return await db.carts.update({
    where: { id: userId, userId },
    data: {
      items: newItems,
      total: newTotal,
      updatedAt: new Date()
    }
  });
}

// Get user's cart (fast point read)
const cart = await db.carts.findUnique({
  where: {
    id: userId,
    userId
  }
});

if (!cart) {
  // Cart expired or doesn't exist
  return { items: [], total: 0 };
}

async function checkout(userId: string) {
  const cart = await db.carts.findUnique({
    where: { id: userId, userId }
  });
  
  if (!cart || cart.items.length === 0) {
    throw new Error('Cart is empty');
  }
  
  // Create order (in different container)
  const order = await db.orders.create({
    data: {
      id: generateId(),
      userId: userId,
      items: cart.items,
      total: cart.total,
      status: 'pending',
      createdAt: new Date()
    }
  });
  
  // Clear cart (or let TTL expire it)
  await db.carts.delete({
    where: { id: userId, userId }
  });
  
  return order;
}