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This example demonstrates how to bridge USDC from Arbitrum to Polygon and automatically supply it to Aave V3 using a hook.

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Overview

You’ll learn how to:
  • Configure a hook to call Aave’s supply function
  • Generate calldata for the Aave Pool contract
  • Create a bridge order with the dlnHook parameter
  • Handle token approvals and transaction execution

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Complete Example

This example bridges 2 USDC from Arbitrum to Polygon and supplies it to Aave V3 in a single cross-chain operation.

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Generate Aave Calldata

First, create the calldata for Aave’s supply() function:
/home/daytona/workspace/source/src/utils/hooks.ts
import { ethers, Interface } from "ethers";
import { USDC } from "./tokens";

export async function generateAaveSupplyCalldata(senderAddress: string) {
  const usdcDecimals = 6;

  // Define arguments for the supply function
  const assetAddress = USDC.POLYGON; // USDC on Polygon
  const supplyAmount = ethers.parseUnits("1", usdcDecimals);
  const onBehalfOfAddress = senderAddress;
  const referralCode = 0;

  const aavePoolAbi = new ethers.Interface([
    "function supply(address asset, uint256 amount, address onBehalfOf, uint16 referralCode)"
  ]);

  // Create the calldata
  const calldata = aavePoolAbi.encodeFunctionData("supply", [
    assetAddress,
    supplyAmount,
    onBehalfOfAddress,
    referralCode
  ]);

  console.log("Aave Pool Supply Calldata:", calldata);
  return calldata;
}

​
Configure the Hook

Set up your bridge order with the dlnHook parameter:
/home/daytona/workspace/source/src/scripts/hooks/evm-evm/basic.ts
import { ethers, Wallet } from "ethers";
import { deBridgeHookInput } from '../../../types';
import { createDebridgeBridgeHook } from '../../../utils/deBridge/createDeBridgeHook';
import { USDC } from '../../../utils/tokens';
import { generateAaveSupplyCalldata } from '../../../utils/hooks';
import { CHAIN_IDS } from '../../../utils/chains';

const usdcDecimals = 6;
const amountToSend = "2"; // 2 USDC
const aavePoolPolygonAddress = "0x794a61358D6845594F94dc1DB02A252b5b4814aD";

const amountInAtomicUnit = ethers.parseUnits(amountToSend, usdcDecimals);
const hookCalldata = await generateAaveSupplyCalldata(senderAddress);

const hookInput: deBridgeHookInput = {
  srcChainId: CHAIN_IDS.Arbitrum.toString(),
  srcChainTokenIn: USDC.ARBITRUM,
  srcChainTokenInAmount: amountInAtomicUnit.toString(),
  dstChainId: CHAIN_IDS.Polygon.toString(),
  dstChainTokenOut: USDC.POLYGON,
  dstChainTokenOutRecipient: senderAddress,
  account: senderAddress,
  srcChainOrderAuthorityAddress: wallet.address,
  dstChainOrderAuthorityAddress: wallet.address,
  dlnHook: {
    type: 'evm_transaction_call',
    data: {
      to: aavePoolPolygonAddress,
      calldata: hookCalldata,
      gas: 0
    }
  }
};

​
Create and Execute the Order

Create the bridge order and execute the transaction: 
// Create the order
const order = await createDebridgeBridgeHook(hookInput);

if (!order?.tx?.to || !order?.tx?.data) {
  throw new Error("Invalid transaction request");
}

console.log("Order Estimation:", order.estimation);

​
Approve Token Spending

Approve the deBridge contract to spend your USDC: 
const tokenContract = new Contract(
  hookInput.srcChainTokenIn,
  erc20Abi,
  signer
);

const requiredAmount = BigInt(order.estimation.srcChainTokenIn.amount);
const currentAllowance = await tokenContract.allowance(
  senderAddress,
  order.tx.to
);

if (currentAllowance < requiredAmount) {
  console.log("Approving token spending...");
  const approveTx = await tokenContract.approve(
    order.tx.to,
    requiredAmount
  );
  await approveTx.wait();
  console.log("Approval confirmed");
}

​
Send the Transaction

console.log("Sending bridge transaction...");
const txResponse = await signer.sendTransaction(order.tx);

console.log(`Transaction Hash: ${txResponse.hash}`);
console.log(`View on Arbiscan: https://arbiscan.io/tx/${txResponse.hash}`);

// Wait for confirmation
const receipt = await txResponse.wait();

if (receipt.status === 1) {
  console.log("Transaction successful!");
  console.log(`Block: ${receipt.blockNumber}`);
  console.log(`Gas Used: ${receipt.gasUsed.toString()}`);
}

​
Hook Parameter Breakdown

​
dlnHook.type
string
required
Set to evm_transaction_call for EVM destination chains.
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dlnHook.data.to
string
required
The Aave Pool contract address on Polygon: 0x794a61358D6845594F94dc1DB02A252b5b4814aD
​
dlnHook.data.calldata
string
required
ABI-encoded supply() function call generated by generateAaveSupplyCalldata()
​
dlnHook.data.gas
number
required
Set to 0 for automatic gas estimation

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How It Works

  1. You send USDC on Arbitrum to the deBridge contract
  2. A taker fills your order on Polygon
  3. USDC is delivered to your dstChainTokenOutRecipient address
  4. The hook calls Aave’s supply() function
  5. Your USDC is supplied to Aave V3 on Polygon
  6. You receive aTokens representing your deposit
The hook execution happens atomically with the token delivery, ensuring your funds are immediately put to work.

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Token Approvals

You need to approve the Aave Pool to spend your USDC on Polygon before the hook can execute successfully. This approval should be done in advance or handled by your recipient contract.

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Pre-Approval Strategy

For personal wallets, approve the Aave Pool contract before initiating the bridge: 
// On Polygon, approve Aave Pool to spend USDC
const usdcPolygon = new Contract(USDC.POLYGON, erc20Abi, polygonSigner);
const maxApproval = ethers.MaxUint256;

await usdcPolygon.approve(aavePoolPolygonAddress, maxApproval);

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Running the Example

cd ~/workspace/source
npm install
cp .env.example .env
# Add your private key and RPC URLs to .env
npx tsx src/scripts/hooks/evm-evm/basic.ts

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Expected Output

Wallet Address (Signer): 0x...

Creating deBridge order with input: {
  "srcChainId": "42161",
  "srcChainTokenIn": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
  "dstChainId": "137",
  "dlnHook": {
    "type": "evm_transaction_call",
    "data": {
      "to": "0x794a61358D6845594F94dc1DB02A252b5b4814aD",
      "calldata": "0x...",
      "gas": 0
    }
  }
}

Order Estimation: { ... }
Transaction Hash: 0x...
View on Arbiscan: https://arbiscan.io/tx/0x...
Transaction successful!

​
Next Steps

Solana to EVM Hooks

Learn how to use hooks from Solana to EVM chains

API Reference

View the complete order creation API

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