How to use js-conflux-sdk in Conflux network to build a simple DApp

In this article/tutorial, I will show how to use js-conflux-sdk to build a simple DApp.

By using js-conflux-sdk an integrated development library based on the JavaScript language and npm package management, it is possible to develop DApps based on the Conflux network, develop, compile and deploy interesting smart contracts to the Conflux network. I hope that through the recording and sorting of this article, it will be possible for more students who are interested in Conflux, a high-performance public chain, to try to use js-conflux-sdk to develop their projects of interest more conveniently.

Compared with web3 , js-conflux-sdk has made a series of improvements and optimizations to its logic. This article will focus on the method of using the SDK to develop and call related smart contracts. If you are familiar with the method of writing smart contracts, you can use smart contracts to do more interesting things.

Environment configuration

First, you need to install nodejs as the operating environment. Refer to the document complete the deployment of the nodejs environment.

1. Select the folder where you want to store DAPP as your working directory.

2. Run npm's init command in the working directory to create a package.json file, which can help you store key information such as project name, project version, project description, entry point file, project dependency information, etc.:

   npm init -y

3. package.json content of the 061cd27c3c12fa file needs to meet your project configuration. Here is the content corresponding to the DAPP I created:

{
  "name": "contract-project",
  "version": "1.0.0",
  "description": "smart Contract",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Yumingyuan",
  "license": "ISC"
}

In addition, you need to install some necessary dependent packages in the project path through the npm package management tool. The commands are as follows:

npm install solc@0.5.11

The installed version is controlled by the @ operator to ensure that the compiler is compatible with our code.

4. In addition, you need to install JavaScript Conflux Software Development Kit in the same working directory as

npm install js-conflux-sdk

After the installation, you will find a folder node_modules in the corresponding directory, which is automatically generated when the SDK is installed.

Try to develop

1. If you need to write smart contracts, we also need to try to smart contracts using 161cd27c3c145b Solidity a high-level programming language for smart contracts and created to implement smart contracts. The corresponding suffix of the Solidity file is sol . In order to facilitate the development, we have created a contracts folder under the project folder. And save the smart contract code we wrote into ./contracts/test.sol , and its content is as follows:

pragma solidity ^0.5.0;

contract ERC20 {
    
    using SafeMath for uint256;
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
    event Transfer(address indexed from, address indexed to, uint tokens);
    mapping(address => uint256) balances;
    mapping(address => mapping (address => uint256)) allowed;
    string public symbol;
    uint8 public decimals;
    string public  name;
    uint256 private _totalSupply;

    constructor(uint8 _decimals, string memory _symbol, string memory _name, uint256 _total_supply) public{
        decimals = _decimals;
        symbol = _symbol;
        name = _name;
        _totalSupply = _total_supply;
        balances[msg.sender] = _totalSupply;
    }

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }    

    function balanceOf(address tokenOwner) public view returns (uint) {
        return balances[tokenOwner];
    }

    function transfer(address receiver, uint numTokens) public returns (bool) {
        require(numTokens <= balances[msg.sender]);
        balances[msg.sender] = balances[msg.sender].sub(numTokens);
        balances[receiver] = balances[receiver].add(numTokens);
        emit Transfer(msg.sender, receiver, numTokens);
        return true;
    }

    function approve(address delegate, uint numTokens) public returns (bool) {
        allowed[msg.sender][delegate] = numTokens;
        emit Approval(msg.sender, delegate, numTokens);
        return true;
    }

    function allowance(address owner, address delegate) public view returns (uint) {
        return allowed[owner][delegate];
    }

    function transferFrom(address owner, address buyer, uint numTokens) public returns (bool) {
        require(numTokens <= balances[owner]);    
        require(numTokens <= allowed[owner][msg.sender]);
    
        balances[owner] = balances[owner].sub(numTokens);
        allowed[owner][msg.sender] = allowed[owner][msg.sender].sub(numTokens);
        balances[buyer] = balances[buyer].add(numTokens);
        emit Transfer(owner, buyer, numTokens);
        return true;
    }
}

library SafeMath { 
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
      assert(b <= a);
      return a - b;
    }
    
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
      uint256 c = a + b;
      assert(c >= a);
      return c;
    }
}

2. The way to try Solidity programming is to use Remix , which can be compiled by test.sol file written by yourself to Remix, but we have seen another interesting method (the following steps are explained), the screenshot here is only a sample :

3. sol who wrote a special JS script that can be used to compile 061cd27c3c1598. The content is as follows. We save it as compile.js and put test.sol file we wrote ./contracts/test.sol , and at the same time put compile.js under ./ , The logic of this code is to read the contracts folder and save its abi and bytecode as json files, and store them in the ./build folder:

const path = require('path');
const fs = require('fs-extra');
const solc = require('solc');

const sourceFolderPath = path.resolve(__dirname, 'contracts');
const buildFolderPath = path.resolve(__dirname, 'build');


const getContractSource = contractFileName => {
    const contractPath = path.resolve(__dirname, 'contracts', contractFileName);
    return fs.readFileSync(contractPath, 'utf8');
};

let sources = {};

var walk = function (dir) {
    var results = [];
    var list = fs.readdirSync(dir);
    list.forEach(function (file) {
        file = dir + '/' + file;
        var stat = fs.statSync(file);
        if (stat && stat.isDirectory()) {
            results = results.concat(walk(file));
        } else {
            if (file.substr(file.length - 4, file.length) === ".sol") {
                sources = {
                    ...sources,
                    [file]: {
                        content: getContractSource(file)
                    }
                };
            }
            results.push(file);
        }
    });
    return results;
};
walk(sourceFolderPath);

const input = {
    language: 'Solidity',
    sources,
    settings: {
        outputSelection: {
            '*': {
                '*': ['*']
            }
        }
    }
}

console.log('\nCompiling contracts...');
const output = JSON.parse(solc.compile(JSON.stringify(input)));
console.log('Done');

let shouldBuild = true;

if (output.errors) {
    console.error(output.errors);
    // throw '\nError in compilation please check the contract\n';
    for (error of output.errors) {
        if (error.severity === 'error') {
            shouldBuild = false;
            throw 'Error found';
            break;
        }
    }
}

if (shouldBuild) {
    console.log('\nBuilding please wait...');

    fs.removeSync(buildFolderPath);
    fs.ensureDirSync(buildFolderPath);

    for (let contractFile in output.contracts) {
        for (let key in output.contracts[contractFile]) {
            fs.outputJsonSync(
                path.resolve(buildFolderPath, `${key}.json`),
                {
                    abi: output.contracts[contractFile][key]["abi"],
                    bytecode: output.contracts[contractFile][key]["evm"]["bytecode"]["object"]
                },
                {
                    spaces: 2,
                    EOL: "\n"
                }
            );
        }
    }
    console.log('Build finished successfully!\n');
} else {
    console.log('\nBuild failed\n');
}

4. Compile ./Contracts/test.sol compile.js on the command line:

node compile.js

The results of the successful compilation are as follows:

5. You can look at ./build folder and find that the compilation tool has generated a file ERC20.json and SafeMath.json , where ERC20.json is as follows:

{
  "abi": [
    {
      "constant": true,
      "inputs": [],
      "name": "name",
      "outputs": [
        {
          "internalType": "string",
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "delegate",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "approve",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "totalSupply",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "buyer",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "transferFrom",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "decimals",
      "outputs": [
        {
          "internalType": "uint8",
          "name": "",
          "type": "uint8"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [
        {
          "internalType": "address",
          "name": "tokenOwner",
          "type": "address"
        }
      ],
      "name": "balanceOf",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "symbol",
      "outputs": [
        {
          "internalType": "string",
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "receiver",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "transfer",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [
        {
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "delegate",
          "type": "address"
        }
      ],
      "name": "allowance",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "uint8",
          "name": "_decimals",
          "type": "uint8"
        },
        {
          "internalType": "string",
          "name": "_symbol",
          "type": "string"
        },
        {
          "internalType": "string",
          "name": "_name",
          "type": "string"
        },
        {
          "internalType": "uint256",
          "name": "_total_supply",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "constructor"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "tokenOwner",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "spender",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "tokens",
          "type": "uint256"
        }
      ],
      "name": "Approval",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "to",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "tokens",
          "type": "uint256"
        }
      ],
      "name": "Transfer",
      "type": "event"
    }
  ],
  "bytecode": "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"
}

This is not over yet, you need to find bytecode and increase the value corresponding to this key by 0x . The effect after the increase is as follows:

{
  "abi": [
    {
      "constant": true,
      "inputs": [],
      "name": "name",
      "outputs": [
        {
          "internalType": "string",
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "delegate",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "approve",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "totalSupply",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "buyer",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "transferFrom",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "decimals",
      "outputs": [
        {
          "internalType": "uint8",
          "name": "",
          "type": "uint8"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [
        {
          "internalType": "address",
          "name": "tokenOwner",
          "type": "address"
        }
      ],
      "name": "balanceOf",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [],
      "name": "symbol",
      "outputs": [
        {
          "internalType": "string",
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [
        {
          "internalType": "address",
          "name": "receiver",
          "type": "address"
        },
        {
          "internalType": "uint256",
          "name": "numTokens",
          "type": "uint256"
        }
      ],
      "name": "transfer",
      "outputs": [
        {
          "internalType": "bool",
          "name": "",
          "type": "bool"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "function"
    },
    {
      "constant": true,
      "inputs": [
        {
          "internalType": "address",
          "name": "owner",
          "type": "address"
        },
        {
          "internalType": "address",
          "name": "delegate",
          "type": "address"
        }
      ],
      "name": "allowance",
      "outputs": [
        {
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "view",
      "type": "function"
    },
    {
      "inputs": [
        {
          "internalType": "uint8",
          "name": "_decimals",
          "type": "uint8"
        },
        {
          "internalType": "string",
          "name": "_symbol",
          "type": "string"
        },
        {
          "internalType": "string",
          "name": "_name",
          "type": "string"
        },
        {
          "internalType": "uint256",
          "name": "_total_supply",
          "type": "uint256"
        }
      ],
      "payable": false,
      "stateMutability": "nonpayable",
      "type": "constructor"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "tokenOwner",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "spender",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "tokens",
          "type": "uint256"
        }
      ],
      "name": "Approval",
      "type": "event"
    },
    {
      "anonymous": false,
      "inputs": [
        {
          "indexed": true,
          "internalType": "address",
          "name": "from",
          "type": "address"
        },
        {
          "indexed": true,
          "internalType": "address",
          "name": "to",
          "type": "address"
        },
        {
          "indexed": false,
          "internalType": "uint256",
          "name": "tokens",
          "type": "uint256"
        }
      ],
      "name": "Transfer",
      "type": "event"
    }
  ],
  "bytecode": 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}

In order to make it easier for everyone to compare the differences, I can only post all the content here. Please be tolerant and understand. Please be sure to find this difference and add 0x Otherwise, there will be an error in the subsequent deployment of the contract. abi and bytecode written in the same json file is that we only need to read the ERC20.json file to use them to call Conflux to create a smart contract .

6. After the smart contract is compiled, we need to deploy it to the Conflux network. You also need to spend some time to do the following preparations:
7. Refer to how to create a Conflux web wallet create your own Conflux wallet;
8. After logging in to the wallet, click the button to apply for test currency on the page to apply for 100CFX test currency, and subsequent deployment of the contract requires consumption;
9. wallet private key in the left column to get your private key. This private key is only used to deploy the contract. Don't tell others, because you can enter your wallet directly through the private key and cannot be disclosed.
10. The purpose of writing deploy.js is to deploy the written contract to the Conflux network, and the deployment location is where you fill in the contract address corresponding to the private key (there will be an explanation later, don’t worry!)

// 填写您的私钥地址，为了减少信息泄露，我使用的测试账户私钥后20位已使用星号进行替代处理，不要复制我的哈！
const PRIVATE_KEY = '0x2772b19636f1d183a9a2a0d27da2a1d0efb97637b425********************';
// 合约地址
const CONTRACT = '';
const { Conflux } = require('js-conflux-sdk');
const compiled = require(`./build/${process.argv[2]}.json`);
const config = require('./config.json');

async function main() {
  const cfx = new Conflux({
    url: 'http://main.confluxrpc.org',
  });
  const account = cfx.Account(PRIVATE_KEY); // create account instance
  console.log(account.address); 

  // create contract instance
  const contract = cfx.Contract({
      
    abi: compiled.abi,
    bytecode: compiled.bytecode,
  });
  //console.log(contract.address)
  const receipt = await contract.constructor(config["decimals"], config["symbol"], config["name"], config["total_supply"])
    .sendTransaction({ from: account })
    .confirmed();
  console.log("recv:"+receipt.contractCreated); 
}
main().catch(e => console.error(e));

It should be noted that: nonce is the transaction serial number of the account. Every time a transaction (including deployment contract) is initiated, a nonce will be incremented by 1 after successful execution, and if the transaction is not successfully executed, the nonce will not increment by 1 (specified here) nonce, you can also delete it to use the default value of Conflux). When deploying again, the nonce that cannot be executed because there is an error in the system will report that the nonce has an error. The operation effect is shown in the following figure:

const config = require('./config.json'); config.json file read by the 061cd27c3c1f5e statement is as follows, where private_key uses the same private key deploy.js

{
  "private_key": "2772b19636f1d183a9a2a0d27da2a1d0efb97637b425********************",
  "network": "homestead",
  "ERC20": "0x0DEd9F7D82a24099F09AF7831CaB61B31Df10487",
  "name": "Kanchan Coin",
  "symbol": "SNK",
  "total_supply": "1000000000000000000000000",
  "decimals": 18
}

Deployment and invocation

1. The method to run deploy.js is as follows:

node deploy.js <contract_name>

Take the contract we wrote as an example, the method is as follows:

node deploy.js ERC20

It should be noted ERC20 is the command-line parameters, by deploy.js code inside process.argv[2] get help in our program to ./contracts/ folder to find the name test.json and deploy its output as shown below:

2. The program echoed recv:0x846ba74923c670a5aec4e58b7551396b9bed5658 obtain the address of our deployment contract as 0x846ba74923c670a5aec4e58b7551396b9bed5658 , use this address to continue to write the call.js code, access and call the contract:

const { Conflux, util } = require('js-conflux-sdk');
//合约持有者地址
const public_address = '0x17b38613e633c2b8fb4686a3a62b9b782ac5e0ca';
// 部署合约地址的地址，与0x17b38613e633c2b8fb4686a3a62b9b782ac5e0ca关联：上面已经进行解释
const contractAddress = '0x846ba74923c670a5aec4e58b7551396b9bed5658';
const PRIVATE_KEY = '0x2772b19636f1d183a9a2a0d27da2a1d0efb97637b425********************';
const compiled = require(`./build/ERC20.json`)
async function main() {
  const cfx = new Conflux({
    url: 'http://main.confluxrpc.org',
  });
  const contract = cfx.Contract({
    address : contractAddress,
    abi: compiled.abi,
  });
  // 查看供应总量
  let result = await contract.totalSupply();
  console.log("Total supply:"  + result.toString());
  const account = cfx.Account(PRIVATE_KEY);
  
  //查看账户余额
  let balance = await contract.balanceOf(public_address);
  console.log("address:"+public_address+" have balance:"+balance.toString());//这是部署合约的账户公开地址
  
  //尝试进行交易
  let allowance_result=await contract.allowance(public_address,'0x1941E3137aDDf02514cBFeC292710463d41e8196');
  console.log("tx:"+allowance_result);
  
  approve_result=await contract.approve(transfer_address,1000);
  console.log("approve result:"+approve_result);
  //尝试进行转账操作
  let transfer_balance=await contract.balanceOf(transfer_address);
  console.log("address:"+transfer_address+" have balance:"+transfer_balance.toString());
  
  await contract.transfer(transfer_address,100).sendTransaction({
      from: account
  }).confirmed();
  
  let transfer_balance_after=await contract.balanceOf(transfer_address);
  console.log("after transfer address:"+transfer_address+" have balance:"+transfer_balance_after.toString());
  
}
main().catch(e => console.error(e));

3. The result of the call is as follows:

postscript

1. After the above-mentioned environment configuration and this wave of operations, the package.json file has also changed:

   {
     "name": "contract-project",
     "version": "1.0.0",
     "description": "smart Contract",
     "main": "index.js",
     "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
     },
     "author": "Yumingyuan",
     "license": "ISC",
     "dependencies": {
    "ethers": "^5.0.3",
    "fs-extra": "^9.0.1",
    "js-conflux-sdk": "^0.10.3",
    "solc": "^0.5.11"
     }
   }

2. The path file tree of the project is as follows:

   +Contract-project
    -call.js
    -compile.js
    -config.json
    -deploy.js
    +build
        -ERC20.json
        -SafeMath.json
    +contracts
        -test.sol
   -package.json
   -package-lock.json

   ---

Thanks to the community friends: Yu Mingyuan for your hard work~
Acknowledgement: assassin , panpan for guidance and help.