Can I make my contract be available to any account? - ethereum

Question

I am developing a dapp where users can upload photographs and mint them to NFTs. My application uses web3( Alchemy web3), Alchemy, Ropsten and Metamask. I also use Hardhat in order to deploy my contract with the command:
npx hardhat run --network ropsten scripts/deploy.js
First of all I have installed Metamask in my browser(Firefox) and I have created my wallet. I have also used a Ropsten Faucet in order to get some ether. In order to deploy my contract I use my account's private key in hardhat.config.js. The problem is that in this way only my account is able to use the contract. My application is supposed to accept multiple users, each with their own Metamask wallet or configuration, performing their own transactions.
Therefore, can I deploy or change my contract so that it can be used by any user and not just the one who deployed it?
Here is my contract:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;
import "#openzeppelin/contracts/token/ERC721/ERC721.sol";
import "#openzeppelin/contracts/access/Ownable.sol";
import "#openzeppelin/contracts/utils/Counters.sol";
contract NFTminter is ERC721, Ownable {
using Counters for Counters.Counter;
mapping (uint256 => string) private _tokenURIs;
mapping(string => uint256) private hashes;
Counters.Counter private _tokenIdCounter;
constructor() ERC721("MyToken", "PcI") {
}
function _baseURI() internal pure override returns (string memory) {
return "ipfs://";
}
function safeMint(address to, string memory metadataURI) public onlyOwner returns (uint256) {
require(hashes[metadataURI] != 1 , "This metadataURI already exists.");
hashes[metadataURI] = 1;
uint256 tokenId = _tokenIdCounter.current();
_tokenIdCounter.increment();
_safeMint(to, tokenId);
_setTokenURI(tokenId, metadataURI);
return tokenId;
}
function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
require(_exists(tokenId), "ERC721URIStorage: URI set of nonexistent token");
_tokenURIs[tokenId] = _tokenURI;
}
}
Here is my hardhat.config.js:
require("#nomiclabs/hardhat-waffle");
const { MNEMONIC, ALCHEMY_HTTP } = require("./alchemy_secrets.json");
task("accounts", "Prints the list of accounts", async (taskArgs, hre) => {
const accounts = await hre.ethers.getSigners();
for (const account of accounts) {
console.log(account.address);
}
});
module.exports = {
networks: {
ropsten: {
url: ALCHEMY_HTTP,
accounts: ['PRIVATEKEYGOESHERE']
},
},
solidity: "0.8.4",
};
And here is the code which calls the contract and sends the transaction:
import Web3 from "web3";
import CONTRACT_ABI from "../ethContractABI";
import { AbiItem } from "web3-utils";
import {
ROPSTEN_CONTRACT_ADDRESS,
NFT_STORAGE_KEY,
ALCHEMY_API_KEY,
} from "../constants";
import { NFTStorage } from "nft.storage";
import { Contract } from "web3-eth-Contract";
import { AlchemyWeb3, createAlchemyWeb3 } from "#alch/alchemy-web3";
declare global {
interface Window {
ethereum: any;
web3: Web3;
}
}
interface postcardReturn {
ipfsLink?: string | undefined;
tokenID?: number | undefined;
errorMessage?: string | undefined;
}
async function convertToNft(
imageToUpload: File,
etherAddress: string,
privateKey: string
): Promise<postcardReturn> {
try {
await CreateWeb3Object();
const web3 = createAlchemyWeb3(ALCHEMY_API_KEY);
const metadata = await GetNFTmetadata(imageToUpload);
const NFTminter = createNftContract(web3, etherAddress);
//CheckIfTokenExists(NFTminter, metadata, etherAddress);
const receipt = await mintToken(
NFTminter,
metadata,
etherAddress,
web3,
privateKey
);
return {
ipfsLink: metadata.data.image.href,
tokenID: receipt!.events!.Transfer.returnValues.tokenId,
};
} catch (error: any) {
return returnError(error);
}
}
async function GetNFTmetadata(imageToUpload: File) {
const client = new NFTStorage({ token: NFT_STORAGE_KEY });
const metadata = await client.store({
name: "From: User",
description: "IMage to be converted to nft",
image: imageToUpload,
});
return metadata;
}
async function CreateWeb3Object() {
if (window.ethereum) {
try {
const enable = window.ethereum.enable();
return;
} catch (error) {
console.log(error);
}
}
}
async function CheckIfTokenExists(
NFTminter: Contract,
metadata: any,
etherAddress: string
) {
const check = await NFTminter.methods
.safeMint(etherAddress, metadata.url)
.estimateGas((error: any, gasAmount: any) => {
if (error) {
console.error(error);
return "An error has occured";
}
});
}
function createNftContract(web3: any, etherAddress: string) {
const NFTminter = new web3.eth.Contract(
CONTRACT_ABI,
ROPSTEN_CONTRACT_ADDRESS
);
return NFTminter;
}
async function mintToken(
NFTminter: Contract,
metadata: any,
etherAddress: string,
web3: AlchemyWeb3,
privateKey: string
) {
const nonce = await web3.eth.getTransactionCount(etherAddress, "latest");
const tx = {
from: etherAddress,
to: ROPSTEN_CONTRACT_ADDRESS,
nonce: nonce,
gas: 2000000,
maxPriorityFeePerGas: 1999999987,
data: NFTminter.methods
.safeMint(etherAddress, metadata.data.image.href)
.encodeABI(),
};
const signedTx = await web3.eth.accounts.signTransaction(tx, privateKey);
web3.eth.sendSignedTransaction(
signedTx.rawTransaction!
).then(console.log)
.catch(console.log);
const transactionReceipt = await web3.eth.sendSignedTransaction(
signedTx.rawTransaction!
);
console.log(transactionReceipt);
return transactionReceipt;
}
function returnError(error: any) {
if (error.message.includes("Internal JSON-RPC error."))
return {
errorMessage: "Internal JSON-RPC error.",
};
return {
errorMessage: error.message,
};
}
export default convertToNft;
The privateKey variable is given by the user before he clicks the upload button. If I change the account that I use, the exception is thrown in this line:
const signedTx = await web3.eth.accounts.signTransaction(tx, privateKey);
The exception says that the Caller is not the contract owner. I think that what I described as the problem is the issue, because I redeployed my contract with the Metamask account that I use now and I can normally send and sign transactions. However, If I change the account I receive an error.

Answer 1

Your safeMint function has onlyOwner modifier. That's why only contract deployer can use it.