Truffle

Truffle is a powerful tool for contract development assistance.

Environment installation

• Node

Refer to Installing Node.js。

• Truffle

Install Truffle

npm install -g truffle

Execute the following commands after installation:

truffle version

Information displayed similar to the following indicates a successful installation.

Truffle v5.3.3 (core: 5.3.3)
Solidity v0.5.16 (solc-js)
Node v14.16.1
Web3.js v1.3.5

Create Project

Create project directory

mkdir mydapp
cd mydapp/

Use truffle to initialize project

truffle init

After the project is initialized, the directory structure is as follows:

|-- contracts         //Folder, for contract file storage
|-- migrations        //Folder, for deployment script keeping
|-- test              //Folder, for test file keeping
|-- truffle-config.js //Truffle deployment file of this project

Edit configuration file

const HDWalletProvider = require('@truffle/hdwallet-provider');
const fs = require('fs');
const mnemonic = fs.readFileSync(".secret").toString().trim();

module.exports = {

  networks: {
    testnet: {
    mainnet: {
      provider: () => new HDWalletProvider(mnemonic, 'https://rpc.koisan-chain.com'),
      network_id: 312,
      gasPrice: 500000000000
    }
  },

  // Set default mocha options here, use special reporters etc.
  mocha: {
    // timeout: 100000
  },

  // Configure your compilers
  compilers: {
    solc: {
      // version: "^0.6.12",
    }
  }
};

Note: it requires private key to be passed in for Provider, this is the seed phrase for the account you'd like to deploy from. Create a new .secret file in root directory and enter your private key to get started. To export private key from metamask wallet you can go to Account Details, then click button Export Private Key and you will see the private key by enter your password of your account.

Edit Contract

Put the customized contract in the contracts folder and modify the deployment script in the migrations folder

• Deploy Contract

Execute deployment commands

truffle migrate --network testnet

Taking the project MetaCoin for instance. Contract codes are as follows:

pragma solidity >=0.4.25 <0.7.0;

import "./ConvertLib.sol";

// This is just a simple example of a coin-like contract.
// It is not standards compatible and cannot be expected to talk to other
// coin/token contracts. If you want to create a standards-compliant
// token, see: https://github.com/ConsenSys/Tokens. Cheers!

contract MetaCoin {
    mapping (address => uint) balances;

    event Transfer(address indexed _from, address indexed _to, uint256 _value);

    constructor() public {
        balances[tx.origin] = 10000;
    }

    function sendCoin(address receiver, uint amount) public returns(bool sufficient) {
        if (balances[msg.sender] < amount) return false;
        balances[msg.sender] -= amount;
        balances[receiver] += amount;
        emit Transfer(msg.sender, receiver, amount);
        return true;
    }

    function getBalanceInEth(address addr) public view returns(uint){
        return ConvertLib.convert(getBalance(addr),2);
    }

    function getBalance(address addr) public view returns(uint) {
        return balances[addr];
    }
}

Output results are as follows:

Compiling your contracts...
===========================
> Everything is up to date, there is nothing to compile.



Starting migrations...
======================
> Network name:    'testnet'
> Network id:      53
> Block gas limit: 6721975 (0x6691b7)


1_initial_migration.js
======================

   Deploying 'Migrations'
   ----------------------
   > transaction hash:    0xc92b16882582cab42a92ed0272133cdb36291b02561b192fef609110549ca8ae
   > Blocks: 0            Seconds: 0
   > contract address:    0xF73901C6560B5fb487FAbF391C1Ce6b1E1B6B8F6
   > block number:        1
   > block timestamp:     1620896663
   > account:             0x3845970B03eDD143295Ae2B1EaE73Beb1ddFd6f3
   > balance:             99.9967165
   > gas used:            164175 (0x2814f)
   > gas price:           500 gwei
   > value sent:          0 ETH
   > total cost:          0.0032835 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:           0.0032835 ETH


2_deploy_contracts.js
=====================

   Deploying 'ConvertLib'
   ----------------------
   > transaction hash:    0xa94c9b9ecd732990ae7d2a69a20061f2ab6f23c6ac8caa1e0380204d32a831d3
   > Blocks: 0            Seconds: 0
   > contract address:    0x2f32569cD13C389D430384654092275DcD4691E3
   > block number:        3
   > block timestamp:     1620896664
   > account:             0x3845970B03eDD143295Ae2B1EaE73Beb1ddFd6f3
   > balance:             99.99396028
   > gas used:            95470 (0x174ee)
   > gas price:           500 gwei
   > value sent:          0 ETH
   > total cost:          0.0019094 ETH


   Linking
   -------
   * Contract: MetaCoin <--> Library: ConvertLib (at address: 0x2f32569cD13C389D430384654092275DcD4691E3)

   Deploying 'MetaCoin'
   --------------------
   > transaction hash:    0x8079e79c2055b1fcfcaee0f6c9147805b5d3c0046466f695a862e8692ec9ece2
   > Blocks: 0            Seconds: 0
   > contract address:    0xA271b814E956AcE4b5c8d68613B44C245dbfA9a8
   > block number:        4
   > block timestamp:     1620896664
   > account:             0x3845970B03eDD143295Ae2B1EaE73Beb1ddFd6f3
   > balance:             99.98822898
   > gas used:            286565 (0x45f65)
   > gas price:           500 gwei
   > value sent:          0 ETH
   > total cost:          0.0057313 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:           0.0076407 ETH


Summary
=======
> Total deployments:   3
> Final cost:          0.0109242 ETH

Interaction

Enter interactive console

truffle console --network testnet
truffle(testnet)> 

Obtain contract abstraction

truffle(testnet)> let instance = await MetaCoin.deployed()
undefined
truffle(testnet)> instance

Initiate a transaction on console

truffle(testnet)> let accounts = await web3.eth.getAccounts()
truffle(testnet)> instance.sendCoin(accounts[1], 10, {from: accounts[0]})

Initiate a call on console

Take the method of calling contract getBalance as an example:

truffle(testnet)> let balance = await instance.getBalance(accounts[0])
truffle(testnet)> balance.toNumber()