lknix / ethereum-erc721

Non-fungible token implementation for the Ethereum blockchain.

   

ERC-721 Token

This is a complete implementation of the ERC-721 non-fungible token standard for the Ethereum blockchain. This is an open source project build with Truffle framework.

Purpose of this implementation is to provide a good starting point for anyone who wants to use and develop non-fungible tokens on the Ethereum blockchain. Instead of re-implementing the ERC-721 yourself you can use this code which has gone through multiple audits and we hope it will be extensively used by the community in the future.

Structure

Since this is a Truffle project, you will find all tokens in contracts/tokens/ directory. There are multiple implementations and you can select between:

• NFToken.sol: This is the base ERC-721 token implementation (with the support for ERC-165).
• NFTokenEnumerable.sol: This implements optional ERC-721 support for enumeration. It is useful if you want to know the total supply of tokens, to query a token by index, etc.
• NFTokenMetadata.sol: This implements optional ERC-721 meta-data features for the token contract. It implements a token name, a symbol and a distinct URI pointing to a publicly exposed ERC-721 JSON metadata file.

Other files in the directory starting with ERC*.sol are interfaces and define the respective standards.

Requirements

• NodeJS 9.0+ recommended.
• Windows, Linux or Mac OS X.

Installation

NPM

This is an NPM module for Truffle framework. In order to use it as a dependency in your Javascript project, you must install it through the npm command:

$ npm install @0xcert/ethereum-erc721

Source

Clone the repository and install the required npm dependencies:

$ git clone [e-mail]:0xcert/ethereum-erc721.git
$ cd ethereum-erc721
$ npm install

Make sure that everything has been set up correctly:

$ npm run test

Usage

NPM

To interact with package's contracts within JavaScript code, you simply need to require that package's .json files:

const contract = require("@0xcert/ethereum-erc721/build/contracts/NFTokenEnumerable.json");
console.log(contract);

Source

Creating smart contract

The easiest way to start is to create a new file under contracts/tokens/ (e.g. MyNFToken.sol):

pragma solidity ^0.4.23;

import "../tokens/NFTokenMetadata.sol";

contract MyNFToken is NFTokenMetadata {

  constructor(
    string _name,
    string _symbol
  )
    public
  {
    nftName = _name;
    nftSymbol = _symbol;
  }

  function mint(
    address _owner,
    uint256 _id
  )
    onlyOwner
    external
  {
    super._mint(_owner, _id);
  }

  function burn(
    address _owner,
    uint256 _tokenId
  )
    onlyOwner
    external
  {
    super._burn(_owner, _tokenId);
  }

}

That's it. Let's compile the contract:

$ npm run compile

The easiest way to deploy it locally and start interacting with the contract (minting and transferring tokens) is to deploy it on your personal (local) blockchain using Ganache. Follow the steps in the Truffle documentation which are described here.

Deploying on testnet (Ropsten)

Next step is to deploy the contract on the testnet.

Requirements:

• geth
• Wallet with some ether.

Create a new file migrations/2_mytoken_migration.js and put in:

const MyNFTokenContract = artifacts.require('./tokens/MyNFToken.sol');

module.exports = function(deployer) {
  deployer.deploy(MyNFTokenContract, 'MyNFTokenTest', 'MYNFT');
};

Start geth and sync your client with the testnet (can take a little bit):

$ geth console --testnet --light --rpc --rpcaddr "localhost" --rpcport "8545" --rpccorsdomain "*" --rpcapi="db,eth,net,web3,personal,web3"

Open another terminal and create a new account (your "test" account wallet):

$ geth --testnet account new

NOTE: In this example the wallet address is 0x9062dd79d7e4273889b234f6b0c840ca43280af60x9 (make sure you prepend the returned string with 0x yourself). Your account address will be different! And don't forget the passphrase otherwise you won't be able to unlock your new account. Now, go and send some ether to it (you can get some here.

Open project's truffle.js and add the following:

module.exports = {
  networks: {
    'ropsten': {
      host: 'localhost',
      port: 8545,
      network_id: '3', // Ropsten ID 3
      from: '0x9062dd79d7e4273889b234f6b0c840ca43280af60x9', // account address from which to deploy
      gas: 4000000,
    },
  },
};

Next, let's unlock your account:

$ npm run console -- --network ropsten

truffle(ropsten)> web3.personal.unlockAccount("0x9062dd79d7e4273889b234f6b0c840ca43280af6", "<PASSWORD>", 1500)

At last, deploy the contract:

$ npm run migrate -- --network ropsten

You can now interact with the contract. First get the address of the deployed contract:

$ npm run networks

You can also check it on Ropsten etherscan. Then in the truffle console (second terminal):

> const { abi } = require('./build/contracts/MyNFToken.json');
> const account0 = '0x9062dd79d7e4273889b234f6b0c840ca43280af60x9'; // your unlocked account
> const account1 = '0x294a4c90900c0dae6ce8e3329a2b219a1f3d8c22'; // another account (you can create it)
> const MyNFTokenContract = web3.eth.contract(abi);
> const MyNFTokenInstance = MyNFTokenContract.at(<MyNFToken ADDRESS>);

> MyNFTokenInstance.symbol();
'MYNFT'
> MyNFTokenInstance.name();
'MyNFToken'
> MyNFTokenInstance.balanceOf(account0).toString();
'0' <-- we don't have any NFTokens yet

> MyNFTokenInstance.mint(account0, '1234', { from: account0 });
'0xd919e28be93d3a597fe8bf8516457f105d47836001dce3e22df7663dc1c5a6ed'
> MyNFTokenInstance.mint(account0, '5678', { from: account0 });
'0x964d082d88f7f4db91e41430b53d5473249470a6823f14fc8d5c3979adb550aa'
> MyNFTokenInstance.balanceOf(account0).toString();
'2' <-- Now we have 2!

> MyNFTokenInstance.burn(account0, '5678', { from: account0 });
> '0xb2b4eede6793212ac2d085d0d1121ce78da26513dc8c3503dc4faadc2f771f58'
> MyNFTokenInstance.balanceOf(account0).toString();
'1'
> MyNFTokenInstance.safeTransferFrom(account0, account1, '1234', { from: account0 });
'0x81b9b353855c4b8c9b8b4d82c4dc8bbfa2de0dd5e6d6d94831b459b1bf0dc7b3'
> MyNFTokenInstance.balanceOf(account0).toString();
'0'
> MyNFTokenInstance.balanceOf(account1).toString();
'1'

Playground

We already deployed some contracts to Ropsten network. You can play with them RIGHT NOW. No need to install software. In this test version of the contract, anybody can mint or burn tokens, so don't use it for anything important.

Contract	Token address	Transaction hash
NFToken	0xb1ee8eafdb07741733df0d0beec3dcf90afa686f	0x1e4d42fb3851139f6c7d89d9e693b5d23faa9bdf45eb41176ea4994c75135faa
NFTokenEnumerable	0xcb99ec15bd8ced42d9f45dac00c20f96fe55383e	0xe3df00103e56372d8e01b1c919796f509b492e65259b0fb7cce4d4cd7d068ed1
NFTokenMetadata	0x39a8e6a0376b280219dd57d292fad7fa6f78dc21	0x63b3fb48de98554ec7a830b293e6680092e3e564459d96c2b5bc61ecc463b36e
NFTokenMetadataEnumerable	0x1d8d5d7cb153e24fce1b4041faa55744d185bef6	0x53d8df5629873a858947e8f9cd0aee9f301f8f8dff3c622d94f52fe6383e451c

Contributing

See CONTRIBUTING.md for how to help out.

Licence

See LICENSE for details.