SystemDesign.md

Table of Contents

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• Table of Contents
  • 1. Shopping Cart
    • Purpose
    • Basic Functions
    • Cache Data Storage
    • Core Data Storage
      • MYSQL or Other SQL Databases
      • Redis or Other NoSQL Databases (Optimal)

1. Shopping Cart

Purpose

A shopping cart temporarily stores selected items before purchase.

Basic Functions

• Add items to Cart.
  • If the user is not logged in, save items to the browser cache.
  • If the user logs in, merge cached items with server-side user data.
  • If the user logs out, sync cart items across all platforms (browser, mobile, etc.).
• Display cart items
• Checkout selected items.

Cache Data Storage

Cookie or LocalStorage Storage:

• Cookie: for small data (< 4KB).
• LocalStorage: for larger data.

Data Structure:

• Cart (list)
  • Item
    • sku_id (product ID)
    • quantity
    • timestamp (added time)
    • selected (true/false)

Example:

{
    "cart":[
        {
            "sku_id": 123,
            "quantity": 2,
            "selected": true,
            "timestamp": 1578772233
        }
    ]
}

Core Data Storage

MYSQL or Other SQL Databases

Store persistent cart data in a database table.

Data Structure:

• Cart (table)
  • id
  • user_id
  • sku_id
  • quantity
  • selected
  • timestamp

Redis or Other NoSQL Databases (Optimal)

Use Redis to store temporary cart data per user.

Data Structure:

• KEY (user id)
• VALUE (list)
  • Item
    • skuId (product ID)
    • quantity
    • timestamp
    • selected

Example:

{
    "KEY": 567,
    "VALUE":[
        {
          "skuId": 123,
          "quantity": 2,
          "selected": true,
          "timestamp": 1578772233
        }
    ]
}