Skip to content

Latest commit

 

History

History
96 lines (78 loc) · 3.6 KB

README.md

File metadata and controls

96 lines (78 loc) · 3.6 KB

📌[Project 1] TxnScan: Simple Cryptocurrency Transaction Tracking 💱

  • The Challenge: Build an API endpoint that accepts a cryptocurrency address (Ethereum, for example). It should retrieve the last 5 transactions for that address from a blockchain explorer API (e.g., Etherscan) and store them in MongoDB. Allow users to query for transactions by address and date range.
  • Focus: Exposes knowledge of external APIs, data parsing, and efficient database storage.

1. Core Technologies Used 🛠️

  • Express.js: A web framework for Node.js that handles HTTP requests
  • Web3.js: Library to interact with Ethereum blockchain
  • MongoDB: Database to store transaction data
  • Etherscan API: External service to fetch Ethereum transaction data

2. Key Components 🔑

A. Setup and Configuration

const web3 = new Web3(process.env.ETH_RPC_URL);
const ETHERSCAN_API_KEY = process.env.ETHERSCAN_API_KEY;
  • RPC URL: Connection point to Ethereum network (using Sepolia testnet)
  • Etherscan API: Access to blockchain data without running a full node

B. Main Features 📋

  1. Transaction Fetching (/api/transactions/fetch)

    • Fetches last 5 transactions for an Ethereum address
    • Validates Ethereum addresses using express-validator
    • Stores transactions in MongoDB for quick future access

  2. Transaction Querying (/api/transactions/:address)

    • Retrieves stored transactions with date filtering
    • Supports pagination (100 transactions per request)
    • Data is pre-processed and stored for faster retrieval

  3. Transaction Statistics (/api/transactions/:address/stats)

    • Calculates important metrics:
      • Total number of transactions
      • Total value transferred
      • Average gas used

📌[Project 2] TokenLens: Token Balance Lookup 👀

  • The Challenge: Build an API endpoint that accepts a token contract address and a wallet address. It should query the blockchain (using web3.js) to retrieve the balance of the specified token held by the wallet address and return the balance.
  • Focus: Understanding of token contracts and token balance retrieval through web3.js.

1. Core Setup & Infrastructure 🏗️

const web3 = new Web3(process.env.ETH_RPC_URL);
  • Web3: The gateway to interact with Ethereum blockchain
  • RPC URL: Like a phone line to communicate with Ethereum network
  • Sepolia: A test network for Ethereum (mentioned in the fallback URL)

2. Smart Contract Interface (ABI) 📘

const tokenABI = [
    // balanceOf, symbol, name, decimals functions
];
  • ABI (Application Binary Interface): The "instruction manual" for interacting with smart contracts
  • Functions Included:
    • balanceOf: Check token balance
    • symbol: Get token symbol (like "USDT")
    • name: Get token name (like "Tether USD")
    • decimals: Get token precision (usually 18)

3. API Endpoints 🛣️

A. Token Balance Endpoint (/api/token-balance)

app.post('/api/token-balance', validateRequest, async (req, res) => {
    // ... code
});

What it does:

  • Takes token and wallet addresses
  • Fetches token details and balance
  • Returns formatted data

Smart Features:

  • Parallel data fetching using Promise.all
  • Address normalization for consistency
  • Balance conversion from Wei to Ether
  • Comprehensive error handling

B. Token Info Endpoint (/api/token-info/:tokenAddress)

app.get('/api/token-info/:tokenAddress', async (req, res) => {
    // ... code
});

Purpose:

  • Quick token detail lookup
  • Validates token existence
  • Returns basic token information