Deploy a contract with Hardhat

Hardhat is one of the popular smart contract development frameworks. It is the ZKFair’s preferred framework, and therefore used in the ZKFair as a default for deploying and automatically verifying smart contracts.

This document is a guide on how to deploy a smart contract on the ZKFair network using Hardhat.

Hardhat smart contract

mkdir <project-name>;cd <project-name>
Initialize a project with Hardhat: npx hardhat.
Next, (… To avoid failure … please go slow with this cli dialogue…),
So then,
Press <ENTER> to set the project root.
Press <ENTER> again to accept addition of .gitignore.
Type n to reject installing sample project's dependencies.
The idea here is to postpone installing dependencies to later steps due to a possible version-related bug.

Open the hardhat.config.js file and paste the below code:

require("dotenv").config();
require("@nomicfoundation/hardhat-toolbox");

/** @type import('hardhat/config').HardhatUserConfig */
module.exports = {
solidity: "0.8.9",
paths: {
    artifacts: "./src",
},
networks: {
    zkEVM: {
    url: `https://testnet-rpc.zkfair.io`,
    accounts: [process.env.ACCOUNT_PRIVATE_KEY],
    },
},
};

Note that a different path to artifacts is added so that the React app will be able to read the contract ABI within the src folder.

Add scripts

Create a new file, in the contracts folder, named Counter.sol: touch contracts/Counter.sol.

Copy the below code and paste it in the Counter contract code:

//SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

contract Counter {
uint256 currentCount = 0;

    function increment() public {
        currentCount = currentCount + 1;
    }

    function retrieve() public view returns (uint256){
        return currentCount;
    }
}

Create a new file in the scripts folder deploy-counter.js: touch scripts/deploy-counter.js.

Add the code below to the deploy-counter.js file:

const hre = require("hardhat");

async function main() {
    const deployedContract = await hre.ethers.deployContract("Counter");
    await deployedContract.waitForDeployment();
    console.log(
        `Counter contract deployed to https://testnet-scan.zkfair.io/address/${deployedContract.target}`
    );
}

main().catch((error) => {
    console.error(error);
    process.exitCode = 1;
});

Before compiling the contract, you need to install the toolbox. You may need to change directory to install outside the project. Use this command:
```
npm install --save-dev @nomicfoundation/hardhat-toolbox
```
Compile your contract code (i.e., go back to the project root in the CLI):
```
npx hardhat compile
```
Now run the scripts:
```
npx hardhat run scripts/deploy-counter.js --network zkEVM
```
Here’s an output example:
Counter contract deployed to https://explorer.public.zkevm-test.net/address/0x5FbDB2315678afecb367f032d93F642f64180aa3

Update frontend

The next step is to turn Counter.sol into a dApp by importing the ethers and the Counter file, as well as logging the contract’s ABI.

Include the below code in the App.js file:

import { ethers } from "ethers";
import Counter from "./contracts/Counter.sol/Counter.json";
const counterAddress = "your-contract-address"
console.log(counterAddress, "Counter ABI: ", Counter.abi);

Update the counterAddress to your deployed address.
- It is the hexadecimal number found at the tail-end of the output of the last npx hardhat run ... command and looks like this 0x5FbDB2315678afecb367f032d93F642f64180aa3.
- It must be pasted in the App.js to replace your-contract-address. Be sure to use the deployed address from your own implementation!

Update frontend counter to read from blockchain. Include the below code in the App.js file:

useEffect(() => {
    // declare the data fetching function
    const fetchCount = async () => {
    const data = await readCounterValue();
    return data;
    };

    fetchCount().catch(console.error);
}, []);

async function readCounterValue() {
    if (typeof window.ethereum !== "undefined") {
        const provider = new ethers.providers.Web3Provider(window.ethereum);

        console.log("provider", provider);

        const contract = new ethers.Contract(
            counterAddress,
            Counter.abi,
            provider
        );

        console.log("contract", contract);

        try {
            const data = await contract.retrieve();
            console.log(data);
            console.log("data: ", parseInt(data.toString()));
            setCount(parseInt(data.toString()));
        } catch (err) {
            console.log("Error: ", err);
            alert(
                "Switch your MetaMask network to ZKFair Testnet and refresh this page!"
            );
        }
    }
}

Also, to import useEffect, insert it like this:
```
import { useState, useEffect } from "react";
```
To be able to track a loader, add this to your state:
```
const [isLoading, setIsLoading] = useState(false);
```
- This is within the App() function.

Let frontend counter write to the blockchain by adding the below requestAccount and updateCounter functions:

async function requestAccount() {
await window.ethereum.request({ method: "eth_requestAccounts" });
}

async function updateCounter() {
if (typeof window.ethereum !== "undefined") {
    await requestAccount();
    const provider = new ethers.providers.Web3Provider(window.ethereum);
    console.log({ provider });
    const signer = provider.getSigner();
    const contract = new ethers.Contract(counterAddress, Counter.abi, signer);
    const transaction = await contract.increment();
    setIsLoading(true);
    await transaction.wait();
    setIsLoading(false);
    readCounterValue();
}
}

Place these two functions above the readCounterValue() function in the App.js file.

Replace the incrementCounter function with this one:

const incrementCounter = async () => {
await updateCounter();
};

Update the increment button code to:

<Button
onClick={incrementCounter}
variant="outlined"
disabled={isLoading}
>
{isLoading ? "loading..." : "+1"}
</Button>

Now, run the Counter dApp by simply using npm start in CLI at the project root.

Congratulations for reaching this far. You have successfully deployed a dApp on the ZKFair testnet.

Last updated 11 months ago