Using Remix

Remix is an open-source, web-based development environment tailored for EVM smart contract development. It offers developers a comprehensive suite of tools for writing, deploying, and testing smart contracts in Solidity. For more information, visit Remix.

Add the Flow Network to MetaMask

Navigate to the Using EVM page to find the button to add the Flow network information to your metamask.

Fund Your Flow Account

Navigate to the Flow Previewnet Faucet to obtain FLOW tokens necessary for deploying a smart contract.

Deploying a Smart Contract Using Remix

HelloWorld Smart Contract

_25

// SPDX-License-Identifier: MIT

_25

pragma solidity ^0.8.0;

_25

_25

contract HelloWorld {

_25

// Declare a public field of type string.

_25

string public greeting;

_25

_25

// Constructor to initialize the greeting.

_25

// In Solidity, the constructor is defined with the "constructor" keyword.

_25

constructor() {

_25

greeting = "Hello, World!";

_25

}

_25

_25

// Public function to change the greeting.

_25

// The "public" keyword makes the function accessible from outside the contract.

_25

function changeGreeting(string memory newGreeting) public {

_25

greeting = newGreeting;

_25

}

_25

_25

// Public function that returns the greeting.

_25

// In Solidity, explicit return types are declared.

_25

function hello() public view returns (string memory) {

_25

return greeting;

_25

}

_25

}

Steps to Deploy the HelloWorld Smart Contract

1. Create a file named HelloWorld.sol.
2. Select Solidity Compiler and compile HelloWorld.sol.
3. Select Deploy & Run Transactions.
4. Make sure to select Injected Provider - Metamask in Environment dropdown.
5. Deploy the HelloWorld smart contract.

Calling the Deployed Smart Contract

Using Ethers.js to Call the HelloWorld Smart Contract

1. Create a new get-greeting.js file under scripts.
2. Paste in the JavaScript code below.
3. Click on green play button to run.
4. Verify the greeting is "Hello World!".

_28

// Import ethers from the ethers.js library

_28

const { ethers } = require('ethers');

_28

_28

// Define the contract ABI

_28

const contractABI = [

_28

"function hello() public view returns (string memory)"

_28

];

_28

_28

// Define the contract address

_28

const contractAddress = "0x8a120383e6057b1f3aef4fa9b89c2f1b0a695926";

_28

_28

// Connect to the Ethereum network

_28

// This example uses the default provider from ethers.js, which connects to the Ethereum mainnet.

_28

// For a testnet or custom RPC, use ethers.getDefaultProvider('networkName') or new ethers.providers.JsonRpcProvider(url)

_28

const provider = new ethers.providers.Web3Provider(window?.ethereum);

_28

_28

_28

// Create a new contract instance

_28

const contract = new ethers.Contract(contractAddress, contractABI, provider);

_28

_28

// Call the hello function of the contract

_28

async function getGreeting() {

_28

const greeting = await contract.hello();

_28

console.log(greeting);

_28

}

_28

_28

// Execute the function

_28

getGreeting();

Follow the steps below to change the greeting and retrieve the new greeting.

Updating the Deployed Smart Contract

1. Select the HelloWorld.sol file.
2. Select the Deploy and Run Transaction page.
3. Make sure to select Injected Provider - Metamask in Environment dropdown.
4. Type a new greeting in the text input next to orange changeGreeting button.
5. Click on the orange changeGreeting button.
6. Sign the Metamask transaction.
7. Verify the greeting has changed by re-running get-greeting.js script above.