The document outlines a simple e-commerce schema detailing product management, category navigation, cart operations, and checkout processes. It includes MongoDB commands for updating products, managing cart status, and handling inventory changes, ensuring accurate order processing. Overall, it serves as a comprehensive guide for implementing a basic e-commerce system.

1. Simple e-commerce schema
Christian Kvalheim @christkv

2. Agenda
• The product
• The categories
• Product by categories
• Category navigation
• The cart
• Add product to cart
• Remove product from cart
• Expire cart
• The checkout

3. The product
{
sku: "111445GB3",
title: "Simsong One mobile phone",
description: "The greatest Onedroid phone on the market .....",
manufacture_details: {
model_number: "A123X",
release_date: new ISODate("2012-05-17T08:14:15.656Z")
},
shipping_details: {
weight: 350,
width: 10,
height: 10,
depth: 1
},
quantity: 99,
pricing: {
price: 1000
}
}

4. The product, add categories
db.products.update(
{sku: "111445GB3"},
{$set: { categories: ['mobile/15G', 'mobile/fm'] }});
{
sku: "111445GB3",
title: "Simsong One mobile phone",
description: "The greatest Onedroid phone on the market .....",
manufacture_details: {
model_number: "A123X", release_date: new
ISODate("2012-05-17T08:14:15.656Z")
},
shipping_details: {
weight: 350, width: 10, height: 10, depth: 1
},
quantity: 99,
categories: ['mobile/15G', 'mobile/
fm'],

5. The product, add categories
• Add an index on the categories
db.products.ensureIndex({categories:1 })
• Locate all the products in a category
db.products.find({categories: /^mobile/fm/})
• If we use case sensitive pre-fix regular expressions
we use the btree index and have very fast lookups

6. Categories
{
title: "Mobiles containing a FM radio",
parent: "mobile",
path: "mobile/fm"
}
db.categories.insert({title: "Mobiles containing a FM radio", parent:
"mobile", path: "mobile/fm"})
db.categories.insert({title: "Mobiles with 15G support", parent:
"mobile", path: "mobile/15G"})
db.categories.ensureIndex({parent: 1, path: 1})
db.categories.ensureIndex({path: 1})

7. Categories, queries
• Locate all categories directly under /mobile
db.categories.find({parent: /^mobile/}, {_id: 0, path: 1})
• Locate all the categories under /mobile
db.categories.find({path: /^mobile/}, {_id: 0, path: 1})

8. Adding to Cart

9. Cart, example schema
{
_id: "the_users_session_id",
status:'active'
quantity: 2,
total: 2000,
products: []
}
• Add item to cart
• Update inventory only if we have enough quantity
• Rollback if inventory update fails

10. Cart, add item to cart
db.carts.update({
_id: "the_users_session_id", status:'active'
}, {
$set: { modified_on: ISODate() },
$push: {
products: {
sku: "111445GB3", quantity: 1, title: "Simsong One mobile
phone", price:1000
}
}
});
{
_id: "the_users_session_id",
status:'active'
quantity: 2,
total: 2000,
products: [{sku: "111445GB3", quantity: 1, title: "Simsong One mobile
phone", price:1000}]
}

11. Cart, add to cart, inventory cover
db.products.update({
sku: "111445GB3", quantity: {$gte: 1}
}, {
$inc: {quantity: -1},
$push: {
in_carts: {
quantity:1, id: "the_users_session_id", timestamp: new
ISODate()
}
}
• If we did not update the stock, roll back cart add
if(!db.runCommand({getLastError:1}).updatedExisting) {
db.carts.update({
_id: "the_users_session_id"
}, {
$pull: {products: {sku:"111445GB3"}}
})
}

12. Update Cart

13. Cart, update quantity
db.carts.update({
_id: "the_users_session_id", "products.sku": "111445GB3", status:
"active"
}, {
$set: {
modified_on: new ISODate(),
"products.$.qty": new_quantity
}
})
• Update the quantity in the cart
• new_quantity = 2
• old_quantity = 1
• delta_quantity = new_quantity - old_quantity

14. Cart, update inventory
db.products.update({
sku: "111445GB3",
"in_carts.id": "the_users_session_id",
quantity: {
$gte: 1
}
}, {
$inc: { quantity: (-1)*delta_quantity },
$set: {
"in_carts.$.quantity": new_quantity, timestamp: new ISODate()
}
})
• Attempt to update the inventory
• new_quantity = 2
• old_quantity = 1
• delta_quantity = new_quantity - old_quantity

15. Cart, on failure rollback
if(!db.runCommand({getLastError:1}).updatedExisting) {
db.carts.update({
_id: "the_users_session_id", "products.sku": "111445GB3"
}, {
$set : { "in_carts.$.quantity": old_quantity}
})
}
• If the update fails roll back the cart to the previous
quantity
• new_quantity = 2
• old_quantity = 1
• delta_quantity = new_quantity - old_quantity

16. Expire Carts

17. Cart, expire all the carts
var carts = db.carts.find({status:"expiring"})
for(var i = 0; i < carts.length; i++) {
var cart = carts[i]
for(var j = 0; j < cart.products.length; j++) {
var product = cart.products[i]
db.products.update({
sku: product.sku,
"in_carts.id": cart._id,
"in_carts.quantity": product.quantity
}, {
$inc: {quantity: item.quantity},
$pull: {in_carts: {id: cart._id}}
})
}
db.carts.update({
_id: cart._id,
$set: {status: 'expired'}
})
}

18. Checkout

19. Insert an Order
db.orders.insert({
created_on: new ISODate("2012-05-17T08:14:15.656Z"),
shipping: {
customer: "Peter P Peterson",
address: "Longroad 1343",
city: "Peterburg",
region: "",
state: "PE",
country: "Peteonia",
delivery_notes: "Leave at the gate",
tracking: {
company: "ups", tracking_number: "22122X211SD",
status: "ontruck",
estimated_delivery: new ISODate("2012-05-17T08:14:15.656Z")
},
},
payment: { method: "visa", transaction_id: "2312213312XXXTD" }
products: {
{quantity: 2, sku:"111445GB3", title: "Simsong mobile phone",
unit_cost:1000, currency:"USD"}
}
})

20. Cart, finish up and clean up
db.carts.update({
_id: "the_users_session_id"
}, {
$set: {status:"complete"}
});
• Set the cart status as completed
db.products.update({
"in_carts.id": "the_users_session_id"
}, {
$pull: {in_carts: {id: "the_users_session_id"}}
}, false, true);
• Remove all carts from products

21. Thank you and happy
schemaing
twitter: @christkv