Deploy with Solidity

Introduction

This article shows how to deploy a Solidity smart contract using Hardhat on any of Quai Network’s chains.

Prerequisites

To deploy single chain smart contracts on Quai, we’ll need a few tool-kits and dependencies. Here’s an overview of all of the dependencies we’ll be using:


NodeJS	Javascript runtime environment. Use the LTS version.
hardhat-example	A Hardhat project with sample contracts and deploy scripts for Quai Network.
Quais.js	A JavaScript library for interacting with Quai Network.
@quai/hardhat-deploy-metadata	A Hardhat plugin that pushes contract metadata to IPFS so contracts can be verified on Quaiscan.
@openzeppelin/contracts	Smart contract library used by the sample ERC20 and ERC721 contracts.

Environment Setup

Install Example Repository

Start by cloning the hardhat-example repository, navigating to the Solidity directory we’ll be using for this tutorial, and installing the dependencies via npm.

git clone https://github.com/dominant-strategies/hardhat-example.git
cd hardhat-example/Solidity
npm install

Smart Contracts

The Solidity/ directory comes with 2 sample contracts: ERC20.sol and ERC721.sol inside of the contracts/ directory. Both contracts are implementations derived from the Open Zeppelin library. We’ll be using the ERC20.sol sample contract for this tutorial, but you can also add your own contracts or use contracts from other libraries.

The Quai Network EVM supports Solidity versions up to 0.8.20. Using a newer version of Solidity may result in errors when deploying smart contracts.

Environment Variables

We’ve included a sample environment file, .env.dist, file at the root of the hardhat-example repo to manage token details, private keys, and your RPC URL in a secure fashion.

The .env.dist file is a template file and should not be used as is. You should copy the .env.dist file to a new .env file.This file lives at the root of the hardhat-example repository and serves as the config file for the Solidity/ directory.

Copy the .env.dist file in the root to a new .env file in the repository root using the following command:

cp ../.env.dist ../.env

Open the .env file and add your private key, RPC URL, and token args for the contract you’d like to deploy. The .env file should look like this:

.env

## Sample environment file - change all values as needed

# Unique privkey for the deployment address
CYPRUS1_PK="0x0000000000000000000000000000000000000000000000000000000000000000" # pubkey starting with 0x00

# Chain ID (local: 1337, Orchard testnet: 15000, mainnet: 9)
CHAIN_ID="15000"

# RPC endpoint
RPC_URL="https://orchard.rpc.quai.network"

# ERC20 Arguments
ERC20_NAME="TestERC20"
ERC20_SYMBOL="TE20"
ERC20_INITIALSUPPLY=1000000

# ERC721 Arguments
ERC721_NAME="TestERC721"
ERC721_SYMBOL="TE721"
ERC721_BASE_URI="ipfs://METADATA_CID/"
ERC721_MAX_TOKENS=1000

The sample .env.dist targets Orchard testnet so you can deploy without spending real QUAI. To deploy to mainnet, change CHAIN_ID to 9 and RPC_URL to https://rpc.quai.network.

Further information on RPC endpoints can be found on the Networks page. The hardhat-example repository uses the Quais SDK to configure network connections using only a single RPC URL. To learn more about how the SDK configures network providers, visit the SDK provider examples section. After filling in your private key and RPC URL, we’re now ready to securely consume them inside of hardhat.config.js.

Hardhat Configuration

Hardhat uses a hardhat.config.js file to configure smart contract deployments. The config file allows you to define deployment networks, tasks, compilers, etc. hardhat-example contains a prebuilt hardhat.config.js file with configuration for deploying and verifying smart contracts on Cyprus-1.

Sample hardhat configuration file

This sample configuration file is provided as part of the hardhat-example repository.

hardhat.config.js

/**
 * @type import('hardhat/config').HardhatUserConfig
 */

require('@nomicfoundation/hardhat-toolbox')
require('@quai/quais-upgrades')
require('@quai/hardhat-deploy-metadata')

const dotenv = require('dotenv')
dotenv.config({ path: '../.env' })

module.exports = {
  defaultNetwork: 'cyprus1',
  networks: {
    cyprus1: {
      url: process.env.RPC_URL,
      accounts: [process.env.CYPRUS1_PK],
      chainId: Number(process.env.CHAIN_ID),
    },
  },

  solidity: {
    compilers: [
      {
        version: '0.8.17',
        settings: {
          optimizer: { enabled: true, runs: 1000 },
          metadata: {
            bytecodeHash: 'ipfs',
            useLiteralContent: true,
          },
          evmVersion: 'london',
        },
      },
      {
        version: '0.8.20',
        settings: {
          optimizer: { enabled: true, runs: 1000 },
          metadata: {
            bytecodeHash: 'ipfs',
            useLiteralContent: true,
          },
          evmVersion: 'london',
        },
      },
    ],
  },

  paths: {
    sources: './contracts',
    cache: './cache',
    artifacts: './artifacts',
  },
  mocha: {
    timeout: 20000,
  },
}

Cyprus-1 is currently the only active zone on Quai Network, so the sample config defines a single cyprus1 network. See Networks for the full list of zone endpoints.

The metadata.bytecodeHash: 'ipfs' and useLiteralContent: true compiler settings are required for @quai/hardhat-deploy-metadata to produce verifiable output. Removing them will break Quaiscan verification.

When deploying a contract, hardhat.config.js pulls your private key and RPC URL from the .env file. You can also specify the Solidity version and compiler settings in the solidity object.

Deploy and Interact

Compile with Hardhat

Smart contract compilation with Hardhat is simple and can be done using npx in the CLI.Compile all of the contracts inside the contracts/ directory with:

npx hardhat compile

Which should output:

Downloading compiler 0.8.20

Compiled 2 Solidity files successfully

Configure deployment scripts

Inside the scripts/ directory, you’ll find a deploy script for both the ERC20 and ERC721 contracts: deployERC20.js and deployERC721.js. For this tutorial, we’ll be deploying an ERC20 contract.The deployERC20.js script pulls your network configuration from hardhat.config.js and your token arguments from the .env file at the root of the repository and uses them to deploy your contract.Token arguments are consumed via the tokenArgs array:

const tokenArgs = [process.env.ERC20_NAME, process.env.ERC20_SYMBOL, quais.parseUnits(process.env.ERC20_INITIALSUPPLY)]

Before the contract is deployed, the script uses the @quai/hardhat-deploy-metadata plugin to push the compiled contract’s metadata to IPFS and returns the resulting CID:

const { deployMetadata } = require("hardhat")
// ...
const ipfsHash = await deployMetadata.pushMetadataToIPFS("ERC20")

The CID is then passed as the fourth argument to ContractFactory, which embeds it in the deployed bytecode. Quaiscan reads that CID later to fetch your source for verification — without it, the contract can be deployed but not verified.

const provider = new quais.JsonRpcProvider(hre.network.config.url, undefined, { usePathing: true })
const wallet = new quais.Wallet(hre.network.config.accounts[0], provider)
const ERC20 = new quais.ContractFactory(ERC20Json.abi, ERC20Json.bytecode, wallet, ipfsHash)

We’ll use these ideas to properly modify the token args and network specification to deploy our contract in the next step.

The deployERC721.js script follows the same structure with different contract arguments and a different ABI/bytecode. You can replicate this configuration for any contract you’d like to deploy.

Deploy your contract

The deploy script takes in a --network flag to specify the network you’d like to deploy to. The sample config only defines cyprus1, which we’ll use here.

npx hardhat run scripts/deployERC20.js --network cyprus1

Which should output:

File added with CID: QmPCoBa1bCFmRoTD7GuexJqBAy7pqg8J4b8B48q5DgxUEV
Original IPFS hash found in bytecode: QmPCoBa1bCFmRoTD7GuexJqBAy7pqg8J4b8B48q5DgxUEV
Metadata JSON for ERC20 saved to /.../hardhat-example/Solidity/metadata/ERC20_metadata.json
Transaction broadcasted: 0x235fdeb85db5b6cee8da9780e2246907e8342751849f5ce3514847a5dffd916f
Contract deployed to:  0x00735E9B2c731Fd3eCC8129a3653ACb99dF969cC

The CID printed in the first line is the IPFS hash you’ll need to verify the contract on Quaiscan — save it.Congratulations, you’ve now deployed an ERC20 token to Quai Network!

The ERC20.sol and ERC721.sol sample contracts are basic implementations of each token for example purposes. It is highly recommended to modify these contracts to fit your specific use case before deploying them for any production use.

Interact with the contract

Hardhat console does not currently offer support for interaction with smart contracts on Quai Network.To interact with the contract, you can configure a simple script using the Quais SDK. The script below configures a Contract instance for the ERC20 token we deployed to 0x00735E9B2c731Fd3eCC8129a3653ACb99dF969cC to get the name, symbol, and total supply of the token.

getContractDetails.js

const quais = require('quais')
const ERC20Json = require('../artifacts/contracts/ERC20.sol/ERC20.json')

async function getContractDetails() {
  // Config provider, wallet, and contract factory
  const provider = new quais.JsonRpcProvider(hre.network.config.url, undefined, { usePathing: true })
  const wallet = new quais.Wallet(hre.network.config.accounts[0], provider)
  const ERC20 = new quais.Contract("0x00735E9B2c731Fd3eCC8129a3653ACb99dF969cC", ERC20Json.abi, wallet)

  const tokenName = await ERC20.name()
  const tokenSymbol = await ERC20.symbol()
  const tokenDecimals = await ERC20.decimals()
  const tokenTotalSupply = await ERC20.totalSupply()
}

getContractDetails()
  .then(() => process.exit(0))
  .catch((error) => {
    console.error(error)
    process.exit(1)
  })

Summary

Now you have all the tools you need to create a simple Hardhat project, deploy, and interact with your own smart contracts. Because the deploy script pushed your contract’s metadata to IPFS, you can now verify it on Quaiscan — see Verifying Contract on Quaiscan for the next step.

Client

Miner

Wallet

Development

Introduction

Prerequisites

Environment Setup

Install Example Repository

Smart Contracts

Environment Variables

Hardhat Configuration

Deploy and Interact

Summary

​Introduction

​Prerequisites

​Environment Setup

​Install Example Repository

​Smart Contracts

​Environment Variables

​Hardhat Configuration

​Deploy and Interact

​Summary

Introduction

Prerequisites

Environment Setup

Install Example Repository

Smart Contracts

Environment Variables

Hardhat Configuration

Deploy and Interact

Summary