Write ERC-721 Contract

It is possible to proceed an ERC-721Let's proceed with the contract deployment process in the order below. contract deployment test using Remix.

Caution

Once deployed contracts cannot be modified or deleted. Please write and deploy the necessary information in the code.

Let's proceed with the contract deployment process in the order below.

• Step 1 : Access the Remix and Create a file

• Step 2 : Write ERC-721 Contract

• Step 3 : Move to SOLIDITY COMPILER tap, Set the version, and Compile

• Step 4 : Set DEPLOY & RUN TRANSACTIONS

• Step 5 : Set Gas fee and Sign at MetaMask

All examples are based on WEMIX3.0 Testnet.

Step 1 : Access the Remix and Create a file

Go to https://remix.ethereum.org.

Remix Initial View

Storage.sol, Owner.sol, and Ballot.sol are shown in the contracts directory. To create a new smart contract, select them to erase it and create a new file.

The figure below shows an example of creatingMyNFT.sol file in the contracts directory.

Create a File

Step 2 : Write ERC-721 Contract

You can create the following ERC-721 contracts:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";

contract MyNFT is ERC721URIStorage, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    constructor() public ERC721("Name", "Symbol") {}

    function mintNFT(address recipient, string memory tokenURI) public onlyOwner returns (uint256){
    
        _tokenIds.increment();

        uint256 newItemId = _tokenIds.current();
        _mint(recipient, newItemId);
        _setTokenURI(newItemId, tokenURI);

        return newItemId;
    }
}

You can specify the Token Name, Token Symbol that you want.

In the code below, you can enter the name and Symbol you want in the 'Name' and 'Symbol'.

    constructor() public ERC721("Name", "Symbol") {}

The figure below is an example of designating 'WMNFT', 'NFT'.

Example Code

Step 3 : Move to SOLIDITY COMPILER tap, Set Version, and Compile

Once the code is written, compile after selecting the correct compiler version on the Solidity Compiler screen.

The compiler version of the example code provided is 0.8.10, and you must select the compiler version that is lower than that version.

Compile Example Code

Step 4 : Set DEPLOY & RUN TRANSACTIONS

On the Deploy & Run Transactions screen, select the environment to deploy smart contracts to test.

The figure below shows an example of deploying to WEMIX3.0 Testnet using the 'Injected Provider - Metamask' provided by Remix.

If ENVIRONEMNT is selected as 'Injected Provider - MetaMask', it is connected to MetaMask, which requires the network to be 'WEMIX_Testnet' connection. For more information about MetaMask connection, see Use MetaMask.

Setting Delpoying Envrionment

Step 5 : Set Gas Fee and Sign at MetaMask

After setting on the Deploy & Run Transactions, if you select 'deploy' button, the MetaMask pop-up appears. The screen showing 'Gas Fee' based on Ethereum will be displayed as shown below.

WEMIX has a different fee policy than Ethereum, so press the 'Site suggested' button to change t the Gas Fee.

MetaMask, default 'Gas fee'

Selecting 'Advanced' on the screen below allows the user to set 'Max priority fee (GWEI)' and 'Max fee (GWEI)' manually.

MetaMask default 'Gas Fee' setting entry screen

'Gas Fee' setting

Currently, WEMIX is using a fixed 'Max priority fee (GWEI)' and the value is 100.

Max fee is a user-defined value and the minimum value is MaxPriorityFee+BASE_FEE.

BASE_FEE in WEMIX is variable according to EIP-1559. Therefore, for a transaction to be successfully created, it is recommended to set it as follows.

1. Max base fee (GWEI) = 101

2. Max priority fee (GWEI) = 100

Complete the Fee setup in the figure above and select 'Save' to be ready for deployment as shown below.

Confirm Example ERC-721 Deployment

Select 'Confirm' in the figure above to proceed with the contract deployment.

If a green check mark appears at the bottom of the Remix screen as shown below, the delpoyment is completed normally.

Complete Example ERC-721 Deployment