Signing Transactions with Web3.py and Metamask Wallet Using Ethers.js
As part of building a decentralized application, it is common to ask users to sign transactions with their MetaMask wallets. To facilitate this process, you will need to use an external wallet solution like Ethereum.js (Ethers.js) in conjunction with the popular web3.py library.
In this article, we will learn how to use ethers.js Metamask details to sign transactions with web3.py in your dApp.
Step 1: Install Dependencies
First, make sure you have the necessary dependencies installed:
npm install ethers ethers-web3
Step 2: Initialize Ethers.js and Web3.py
Create a new file for your dApp’s initialization code, for example, “app.js”:
const Web3 = require('web3');
const Ethers = require('ethers/web3');
// Initialize Ethers.js
const ethers = new Web3(new URL('
Replace “YOUR_PROJECT_ID” with your actual Infura project ID.
Step 3: Get the user’s Metamask details
To get the user’s MetaMask details, you will need to connect their wallet to ethers.js using the ethers.connect() method. You can use a library like ethers-connection to simplify this process:
const ethersConnect = require('ethers-connection');
// Get the user's Metamask wallet address and private key
ethers.connect({
accounts: ['YOUR_METAMASK_ADDRESS'],
}, async(address, private key) => {
// Use these credentials to sign transactions with web3.py later
});
Replace ‘YOUR_METAMASK_ADDRESS’ with your actual MetaMask address.
Step 4: Sign Transactions Using Web3.py
Now that you have the user’s Metamask details, you can use them to sign transactions with web3.py. Create a new file for your dApp’s transaction processing code:
const web3 = require('web3');
// Get the signed address from the connection ethers.js
async function getSignedAddress(address, privateKey) {
const web3Instance = new web3.Web3();
return await web3Instance.eth.accounts.signTransaction({
to: address,
data: '', // You can use your transaction details here
}, privatekey)
.then((signedTx) => signedTx.rawTransaction)
.then((signedTxRaw) => signedTx.rawTransaction);
}
module.exports = { getSignedAddress };
This function takes the user’s Metamask address and private key as arguments, creates a new Web3 instance, signs a transaction with the provided details, and returns the raw transaction.
Putting it all together
Here’s an example of how you can use these functions in your dApp:
const app = require('./app');
// Initialize Ethers.js and Web3.py
require('./initEthers')(ethers);
const { getSignedAddress } = require('./getSignedAddress');
module.exports = async(req, res) => {
const address = 'YOUR_METAMASK_ADDRESS';
const privateKey = 'YOUR_PRIVATE_KEY';
// Get the signed transaction using web3.py and Metamask details
const signedTx = await app.getSignedAddress(address, privateKey);
// Send the signed transaction to Ethers.js for verification
ethers.connect({
accounts : [address],
}, async(account) => {
const txHash = await account.sendTransaction(signedTx);
console.log(Transaction sent to ${txHash.address});
});
};
This example assumes that you have already initialized the getSignedAddress function in your dApp’s main file (app.js). You can replace “YOUR_METAMASK_ADDRESS” and “YOUR_PRIVATE_KEY” with your actual MetaMask credentials.
Conclusion
Signing transactions with Metamask wallets using ethers.js is a simple process that leverages Web3.py for transaction verification. By following these steps, you will be able to integrate your dApp with Ethereum.js solutions like web3.
