Transaction handling in Node.js - Mini Project: Build & Apply

Transaction Handling in Node.js

📖 Scenario: You are building a simple banking system where users can transfer money between accounts. To keep data safe, you need to handle transactions properly so that either the whole transfer happens or nothing happens at all.

🎯 Goal: Build a Node.js script that uses a transaction to transfer money between two accounts safely.

📋 What You'll Learn

Create an initial accounts object with two accounts and their balances

Add a variable to hold the transfer amount

Write a function that performs the transfer inside a transaction

Complete the transaction handling with commit and rollback logic

💡 Why This Matters

🌍 Real World

Handling transactions is crucial in banking and e-commerce to keep data consistent and avoid errors during money transfers or purchases.

💼 Career

Understanding transaction handling is important for backend developers working with databases and APIs to ensure data integrity.

1

Create initial accounts data

Create a constant called accounts as an object with two keys: alice with value 500 and bob with value 300.

Node.js

// Create the accounts object with alice and bob balances
// Your code here

Need a hint?

Use const accounts = { alice: 500, bob: 300 }; to create the object.

2

Add transfer amount variable

Add a constant called transferAmount and set it to 200.

Node.js

const accounts = { alice: 500, bob: 300 };
// Define the transfer amount
// Your code here

Need a hint?

Use const transferAmount = 200; to set the amount to transfer.

3

Write transfer function with transaction logic

Write an async function called transfer that takes no parameters. Inside it, create a variable transactionActive set to true. Then subtract transferAmount from accounts.alice and add it to accounts.bob. If accounts.alice becomes negative, set transactionActive to false.

Node.js

const accounts = { alice: 500, bob: 300 };
const transferAmount = 200;

// Write async function transfer
// Your code here

Need a hint?

Define the function with async function transfer(). Use let transactionActive = true; and update balances. Check if accounts.alice is negative to set transactionActive to false.

4

Complete transaction with commit or rollback

Inside the transfer function, after the balance changes, add an if statement that checks transactionActive. If true, add a comment // Commit transaction. Else, add a comment // Rollback transaction and reset accounts.alice to 500 and accounts.bob to 300.

Node.js

const accounts = { alice: 500, bob: 300 };
const transferAmount = 200;

async function transfer() {
    let transactionActive = true;
    accounts.alice -= transferAmount;
    accounts.bob += transferAmount;
    if (accounts.alice < 0) {
        transactionActive = false;
    }
    // Add commit or rollback logic here
// Your code here
}

Need a hint?

Use if (transactionActive) { /* commit */ } else { /* rollback */ } and reset balances on rollback.