How do I accept an ERC20 token for Nft mint payment instead of ETH - solidity

Question

How do I accept an ERC 20 token for minting NFTS on my smart contract. I’m currently paying for the minting using ETH, and I will like to accept another ERC 20 token.

Answer 1

You can change your mint function in order to accept the preferred token type as payment. And in order to prevent paying gas in eth, you can use biconomy forward.Check out their docs.
https://docs.biconomy.io/products/enable-paying-gas-in-erc20

Answer 2

You need a reference from the NFT contract to your token contract.
Let's say we have these two contracts: NFTContract, TokenContract.
contract NFTContract {
TokenContract tokenContract;
...
mint() {
tokensContract.transfer(msg.sender(), addressReceiver, tokensToSend);
...
}
}
contract TokenContract {
transfer(sender, receiver, balance) {}
}
You can check an example of how I did this in my repo I'm developing for my thesis.
https://github.com/NickVanzo/Contracts_For_Thesis

Answer 3

Maybe it will work for you but be careful you can take errors for solidity versions.
pragma solidity ^0.8.9;
import "#openzeppelin/contracts/token/ERC721/ERC721.sol";
import "#openzeppelin/contracts/token/ERC721/extensions/ERC721Burnable.sol";
import "#openzeppelin/contracts/access/Ownable.sol";
import "#openzeppelin/contracts/token/ERC20/ERC20.sol";
contract LSTNFT is ERC721, ERC721Burnable, Ownable {
uint256 public cost;
uint256 maxSupply = 20;
uint256 maxMintAmountPerTx = 2;
// address of the ERC-20 contract
address public erc20Contract = "ERC-20 address is here";
// instance of the ERC-20 contract
ERC20 public erc20;
constructor() ERC721("Lestonz NFT", "LSTN") {
erc20 = ERC20(erc20Contract);
}
function _baseURI() internal pure override returns (string memory) {
return "ipfs://your ipfs url";
}
modifier mintPriceCompliance(uint256 _mintAmount) {
if (msg.sender != owner()) {
require(msg.value >= cost * _mintAmount, 'Insufficient funds!');
}
_;
}
function mint(uint256 _mintAmount) public payable mintPriceCompliance(_mintAmount) {
require(erc20.balanceOf(msg.sender) >= msg.value, "Not enough ERC-20 tokens");
_safeMint(_msgSender(), _mintAmount);
}
function setCost(uint256 _cost) public onlyOwner {
cost = _cost;
}
}