Decentralized Finance (DeFi)

Integrating with Aave Lending Protocol

// Example of depositing and borrowing with Aave V3
// Using ethers.js and @aave/contract-helpers

import { ethers } from 'ethers';
import { Pool } from '@aave/contract-helpers';

async function aaveLendingExample() {
  try {
    // Initialize provider and signer
    const provider = new ethers.providers.Web3Provider(window.ethereum);
    const signer = provider.getSigner();
    const userAddress = await signer.getAddress();
    
    // Initialize Aave Pool contract (Ethereum mainnet example)
    const pool = new Pool(provider, {
      POOL: '0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2', // Aave V3 Pool address
      WETH_GATEWAY: '0xD322A49006FC828F9B5B37Ab215F99B4E5caB19C'
    });
    
    // 1. Supply ETH as collateral
    // Convert 1 ETH to Wei
    const amountToSupply = ethers.utils.parseEther('1.0');
    
    // Prepare supply transaction
    const supplyTx = await pool.supply({
      user: userAddress,
      reserve: '0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE', // ETH address in Aave
      amount: amountToSupply.toString(),
      onBehalfOf: userAddress,
      referralCode: '0'
    });
    
    // Execute transaction
    const supplyTransaction = await signer.sendTransaction(supplyTx);
    console.log('Supply transaction submitted:', supplyTransaction.hash);
    await supplyTransaction.wait();
    console.log('ETH supplied successfully!');
    
    // 2. Borrow USDC using ETH as collateral
    // Fetch reserve data to calculate borrowing capacity
    const userAccountData = await pool.getUserAccountData(userAddress);
    console.log('Available to borrow:', userAccountData.availableBorrowsUSD);
    
    // USDC has 6 decimals
    const amountToBorrow = ethers.utils.parseUnits('100', 6); // Borrow 100 USDC
    
    // USDC address on Ethereum mainnet
    const usdcAddress = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48';
    
    // Prepare borrow transaction (variable rate)
    const borrowTx = await pool.borrow({
      user: userAddress,
      reserve: usdcAddress,
      amount: amountToBorrow.toString(),
      interestRateMode: 2, // Variable rate
      onBehalfOf: userAddress,
      referralCode: '0'
    });
    
    // Execute transaction
    const borrowTransaction = await signer.sendTransaction(borrowTx);
    console.log('Borrow transaction submitted:', borrowTransaction.hash);
    await borrowTransaction.wait();
    console.log('USDC borrowed successfully!');
    
    return {
      supplied: '1 ETH',
      borrowed: '100 USDC',
      transactions: {
        supply: supplyTransaction.hash,
        borrow: borrowTransaction.hash
      }
    };
  } catch (error) {
    console.error('Error in Aave lending example:', error);
    throw error;
  }
}

This code demonstrates how to interact with the Aave lending protocol to supply ETH as collateral and borrow USDC. It uses the official Aave contract helpers library to simplify the process of generating and sending the necessary transactions.