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Metamask: How to Import Locally Generated Addresses on Your Metamask
As a developer working with smart contracts, it’s essential to manage the private keys and addresses of your users securely. One popular solution for this is the MetaMask browser extension, which allows users to interact with their local Ethereum accounts within the browser. However, when you’re building complex applications like connect and fund contracts using Hardhat and Ethers.js, you’ll need to import locally generated addresses from your Metamask wallet.
In this article, we’ll walk through the process of importing locally generated addresses on your MetaMask using your own local wallet.
Why is it necessary?
When users interact with your contract, they typically pass a unique address (e.g., 0x1234567890abcdef
) as an argument to the function. However, when you generate a new public key for your contract’s functions, you need to update the address stored in the contract’s storage.
To achieve this, you’ll need to import the locally generated addresses from your MetaMask wallet. This ensures that you can correctly initialize your contract with the correct private key and account information.
Prerequisites
Before we dive into the process, make sure you have:
- A local Ethereum node set up (e.g., Metamask, Infura, or Geth)
- Your own local MetaMask wallet
- Ethers.js installed in your project
- Hardhat set up to interact with your Ethereum network
Step 1: Create a new address from your MetaMask wallet
First, you’ll need to create a new address on your Metamask wallet that will be used as the contract’s private key. Here’s how:
- Launch the MetaMask browser extension in your web browser.
- Sign in with your MetaMask credentials (or create a new wallet if needed).
- Click on “Settings” and navigate to “Wallet”.
- Click on “Create New Address” or generate a new address using the button.
Name your new address, for example: my_new_address
.
Step 2: Set up Ethers.js
Now that you have your MetaMask wallet’s private key (public key) ready, you’ll need to set it up in your Hardhat project. Here’s how:
- Install ethers.js using npm or yarn:
npm install ethers.js
- Import the
ethers
module into your contract code:
import {.ethers } from '@nomiclabs/ethers';
Step 3: Initialize the contract with locally generated addresses
Create a new function in your contract that accepts an address and updates the contract’s storage accordingly.
Here’s an example implementation for a simple connect and fund contract:
const Ethers = require('@nomiclabs/ethers');
contract('ConnectAndFund', () => {
let privateKey;
letaddress;
async function init() {
// Import locally generated addresses from MetaMask
privateKey = await ethers.Wallet.fromAccounts(address);
address = privateKey.address;
// Initialize the contract with the imported addresses
await new Ethers.Contract(this.constructor, [...contract ABI], this);
}
});
Step 4: Update your Hardhat project
In your hardhat.config.js
file, update the ethersjs
configuration to include the MetaMask wallet:
module.exports = {
// ... other configurations ...
ethersjs: {
accounts: {
mnemonicFile: './metamask.json',
},
},
};
Step 5: Run your contract
To verify that your contract is working correctly, run it on a local Ethereum node using the hardhat run
command:
npx hardhat run scripts/connect-and-fund.js --network mainnet --accounts --private-key
Replace
and
with the actual MetaMask wallet credentials you used for initialization.
That’s it!