I'm running a truffle project created with truffle init command in CMD. then I create a react app with npx reate-react-app in the same folder.
I'm creating a NFT so I have installed OZ contracts in my react app with using npm install @openzeppelin/contracts command.
Now at this point whole project looks like this.
root folder
Package.json
and this is the complete truffle-config.js
/**
* Use this file to configure your truffle project. It's seeded with some
* common settings for different networks and features like migrations,
* compilation and testing. Uncomment the ones you need or modify
* them to suit your project as necessary.
*
* More information about configuration can be found at:
*
* trufflesuite.com/docs/advanced/configuration
*
* To deploy via Infura you'll need a wallet provider (like @truffle/hdwallet-provider)
* to sign your transactions before they're sent to a remote public node. Infura accounts
* are available for free at: infura.io/register.
*
* You'll also need a mnemonic - the twelve word phrase the wallet uses to generate
* public/private key pairs. If you're publishing your code to GitHub make sure you load this
* phrase from a file you've .gitignored so it doesn't accidentally become public.
*
*/
// const HDWalletProvider = require('@truffle/hdwallet-provider');
// const infuraKey = "fj4jll3k.....";
//
// const fs = require('fs');
// const mnemonic = fs.readFileSync(".secret").toString().trim();
const path = require("path");
module.exports = {
contracts_build_directory: path.join(__dirname, "client/src/contracts"),
/**
* Networks define how you connect to your ethereum client and let you set the
* defaults web3 uses to send transactions. If you don't specify one truffle
* will spin up a development blockchain for you on port 9545 when you
* run `develop` or `test`. You can ask a truffle command to use a specific
* network from the command line, e.g
*
* $ truffle test --network <network-name>
*/
networks: {
// Useful for testing. The `development` name is special - truffle uses it by default
// if it's defined here and no other network is specified at the command line.
// You should run a client (like ganache-cli, geth or parity) in a separate terminal
// tab if you use this network and you must also set the `host`, `port` and `network_id`
// options below to some value.
//
development: {
host: "127.0.0.1", // Localhost (default: none)
port: 7545, // Standard Ethereum port (default: none)
network_id: "*", // Any network (default: none)
},
// Another network with more advanced options...
// advanced: {
// port: 8777, // Custom port
// network_id: 1342, // Custom network
// gas: 8500000, // Gas sent with each transaction (default: ~6700000)
// gasPrice: 20000000000, // 20 gwei (in wei) (default: 100 gwei)
// from: <address>, // Account to send txs from (default: accounts[0])
// websocket: true // Enable EventEmitter interface for web3 (default: false)
// },
// Useful for deploying to a public network.
// NB: It's important to wrap the provider as a function.
// ropsten: {
// provider: () => new HDWalletProvider(mnemonic, `https://ropsten.infura.io/v3/YOUR-PROJECT-ID`),
// network_id: 3, // Ropsten's id
// gas: 5500000, // Ropsten has a lower block limit than mainnet
// confirmations: 2, // # of confs to wait between deployments. (default: 0)
// timeoutBlocks: 200, // # of blocks before a deployment times out (minimum/default: 50)
// skipDryRun: true // Skip dry run before migrations? (default: false for public nets )
// },
// Useful for private networks
// private: {
// provider: () => new HDWalletProvider(mnemonic, `https://network.io`),
// network_id: 2111, // This network is yours, in the cloud.
// production: true // Treats this network as if it was a public net. (default: false)
// }
},
// Set default mocha options here, use special reporters etc.
mocha: {
// timeout: 100000
},
// Configure your compilers
compilers: {
solc: {
version: "0.6.1", // Fetch exact version from solc-bin (default: truffle's version)
// docker: true, // Use "0.5.1" you've installed locally with docker (default: false)
// settings: { // See the solidity docs for advice about optimization and evmVersion
// optimizer: {
// enabled: false,
// runs: 200
// },
// evmVersion: "byzantium"
// }
}
},
// Truffle DB is currently disabled by default; to enable it, change enabled: false to enabled: true
//
// Note: if you migrated your contracts prior to enabling this field in your Truffle project and want
// those previously migrated contracts available in the .db directory, you will need to run the following:
// $ truffle migrate --reset --compile-all
db: {
enabled: false
}
};
in my solidity contract file, path is C:\Dapp\Pet-Shop-IPFS-React\contracts\PetShop.sol, I've imported the installed OZ ERC721 contract PetShop.js
pragma solidity >=0.4.22 <0.9.0;
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
contract PetShop is ERC721 {
uint256 public tokenId;
uint256 public prevOwnerTokenID;
address public owner;
mapping(uint256 => uint256) public priceMapping;
mapping(uint256 => string) tokenIdToOffchainContentHash;
event PetGenerated(address, uint256, uint256, string);
event BuyPet(uint256, address, address);
event SuccessfulEtherWithdrawal(uint256, address, bool);
constructor()
ERC721("ShanBuilders", "SBRS")
{
owner = msg.sender;
}
function generatePet(uint256 _petPrice, string memory contentHash) public returns(bool) {
require(msg.sender != address(0), "Please! Check back! Registeration should not be from zero address");
require(msg.sender == owner, "Only contract owner can generate more pets");
tokenId++;
require(tokenId <= 16, "More than 16 pets is not allowed");
priceMapping[tokenId] = _petPrice;
tokenIdToOffchainContentHash[tokenId] = contentHash;
_mint(owner, tokenId);
emit PetGenerated(owner, tokenId, _petPrice, contentHash);
return true;
}
function checkPrice(uint256 _tokenId) public view returns(uint256) {
return priceMapping[_tokenId];
}
function checkHashForAToken(uint256 _tokenId) public view returns(string memory) {
return tokenIdToOffchainContentHash[_tokenId];
}
function buyPet(uint256 _tokenId) public payable returns(bool, string memory) {
prevOwnerTokenID = _tokenId;
address buyer = msg.sender;
address _owner = ownerOf(prevOwnerTokenID);
require(buyer != address(0), "Should not be zero address");
require(_exists(prevOwnerTokenID), "Invalid property Id, not registered");
require(msg.value == checkPrice(prevOwnerTokenID), "Please Send The Required Value");
withDraw(msg.value);
_transfer(_owner, buyer, prevOwnerTokenID);
emit BuyPet(_tokenId, _owner, buyer);
return (true, "Succesful");
}
function withDraw(uint256 _amount) internal returns(bool) {
address _owner = ownerOf(prevOwnerTokenID);
require(_amount > 0, "Amount must be valid");
payable(_owner).transfer(_amount);
emit SuccessfulEtherWithdrawal(_amount, _owner, true);
return true;
}
}
this is Migration
const PetShop = artifacts.require("PetShop");
module.exports = function (deployer) {
deployer.deploy(PetShop);
};
Q is after doing all this something went wrong that I didn't notice. when i run truffle compile it fails the compilation and throws error,
*** ParserError: Source "@openzeppelin/contracts/token/ERC721/ERC721.sol" not found: File import callback not supported***
How can I work around this issue, It will be great if someone could help me understand what this error says and why this is happening?
import https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol) and see if it works. Note that this requirespragma solidity ^0.8.0– ttoshevtruffle compile --listit shows almost till 0.8.4 compiler versions but when i compile it through truffle with 0.8.0 it shows compiler is running, no output, – sultan