What is ERC721 ?
ERC721 is a standard that describes how to build NFTs on EVM compatible blockchains. We use the OppenZeppelin implementaion of ERC721
Let's make the NFT
First we need to setup the images and the metadata describing each image. We are creating 6 NFTs. So we have 6 images and metadata files in a directory.
The Metadata JSON Schema is given Metadata Schema
{
"name": "MyNFT Collection #1",
"description": "My First NFT.",
"image": "ipfs://imageBaseURI/1.png"
}
Metadata needs the image path. So upload images folder to IPFS first. I used pinata here.
Now use the image directory CID to correct metadata files.
{
"name": "MyNFT Collection #1",
"description": "My First NFT.",
"image": "https://gateway.pinata.cloud/ipfs/<PASTE_CID_HERE>/1.png"
}
Upload the metadata files to the IPFS. Now we have both NFT images and metadata in IPFS.
Now we can deploy the contract and mint the NFT.
Smart Contract
Lets import packages needed.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
Now the contract extends ERC721:
contract MyNFT is ERC721, ERC721URIStorage, Ownable {
uint256 private _nextTokenId;
constructor(address initialOwner)
ERC721("MyNFT", "MNT")
Ownable(initialOwner)
{}
// functions goes here ...
}
Additional functions needed:
function safeMint(address to, string memory uri) public onlyOwner {
uint256 tokenId = _nextTokenId++;
_safeMint(to, tokenId);
_setTokenURI(tokenId, uri);
}
function tokenURI(uint256 tokenId)
public
view
override(ERC721, ERC721URIStorage)
returns (string memory)
{
return super.tokenURI(tokenId);
}
function supportsInterface(bytes4 interfaceId)
public
view
override(ERC721, ERC721URIStorage)
returns (bool)
{
return super.supportsInterface(interfaceId);
}
Deploy contract using hardhat
Install hardhat
npx hardhat init
Get a JSON RPC url from Infura/Alchemy. Setup the hardhat.config.json.
Use the script to deploy and mint the NFT:
const hre = require("hardhat");
async function main() {
// Deploy contract with initial owner address
const contract = await hre.ethers.deployContract("MyNFT", ["0xcF469d3BEB3Fc24cEe979eFf83BE33ed50988502"], {});
await contract.waitForDeployment();
console.log("Contract deployed to:", contract.target);
const uris = [
"https://gateway.pinata.cloud/ipfs/<PASTE_CID_HERE>/1.json",
"https://gateway.pinata.cloud/ipfs/<PASTE_CID_HERE>/2.json",
"https://gateway.pinata.cloud/ipfs/<PASTE_CID_HERE>/3.json",
// Add more URIs as needed
];
for (let i = 0; i < uris.length; i++) {
const recipientAddress = "0xYourRecipientAddressHere"; // Replace with the actual recipient address
await myNFT.safeMint(recipientAddress, uris[i]);
console.log(`Minted NFT with URI ${uris[i]} to address ${recipientAddress}`);
}
}
main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
Now we created and deployed an NFT using ERC721
Top comments (0)