如何从零开始搭建一个Truffle框架的DAPP应用

2018-11-13 本文已影响5人宇宙永恒

image

1 摘要

开发实战|3步教你在以太坊上开一家宠物店（附流程+代码）介绍了如何获取宠物商店的TRUFLLE框架代码，并完成部署的过程。

但是这个是已经成熟的代码框架，一般用户要开发自己的项目。那如何借用宠物商店成熟框架完成自有DAPP的搭建呢？我们以tiny熊老师的一个姓名/年龄智能合约用例来呈现方法。

2 需求描述

我们要实现一个用户姓名和年纪的输入和呈现页面，能更新智能合约上的用户名和年龄。重新输入用户名和年纪，点击按钮可更新智能合约的这2个变量信息。

3 操作步骤

3.1 创建目录，下载框架

首先创建好目录，下载宠物商店的代码框架。

duncanwang@ubuntu:~/work$ mkdir name-age

duncanwang@ubuntu:~/work$ cd name-age

duncanwang@ubuntu:~/work/name-age$ truffle unbox pet-shop

Downloading...

Unpacking...

Setting up...

Unbox successful. Sweet!

Commands:

  Compile:        truffle compile

  Migrate:        truffle migrate

  Test contracts: truffle test

  Run dev server: npm run

 devduncanwang@ubuntu:~/work/name-age$

3.2 创建智能合约代码

新建一个InfoContract.sol智能合约文件，并把它更新到./contracts目录下。

pragma solidity ^0.4.24;

contract InfoContract {

    string name;

    uint age;

    event Instructor(string name, uint age);

    function setInfo(string _name, uint _age) public {

        name = _name;

        age = _age;

        emit Instructor(name, age);

    } 

   function getInfo() public view returns(string, uint) {

        return (name, age);

    }

}

3.3 增加合约相关的部署和测试代码

1）增加合约部署测试

文件2_info_contract.js到./migrations目录，代码如下，表示contract InfoContract合约部署。

var MyContract = artifacts.require("./InfoContract.sol");

module.exports = function(deployer) {

  // deployment steps

  deployer.deploy(MyContract);

};

2）增加测试文件

pragma solidity ^0.4.24;

import "truffle/Assert.sol";

import "truffle/DeployedAddresses.sol";

import "../contracts/InfoContract.sol";

contract TestInfoContract {

   InfoContract info = InfoContract(DeployedAddresses.InfoContract());

   string name;

   uint age;

   function testInfo() {

     info.setInfo("ABC", 10);

     (name, age) = info.getInfo();

     Assert.equal(name, "ABC", "设置名字出错");

     Assert.equal(age, 10, "设置年龄出错");

   }

}

3）修改配置文件

因为默认ganache-cli的端口为8545，所以需要修改truffle.js的端口号由7545 变为8545。

module.exports = {

  // See <http://truffleframework.com/docs/advanced/configuration>

  // for more about customizing your Truffle configuration!

  networks: {

    development: {

      host: "127.0.0.1",

      port: 8545,

      network_id: "*" // Match any network id

    }

  }

};

否则测试时会有找不到客户端提示。

duncanwang@ubuntu:~/work/name-age$ truffle test

Could not connect to your Ethereum client. Please check that your Ethereum client:

    - is running

    - is accepting RPC connections (i.e., "--rpc" option is used in geth)

    - is accessible over the network

    - is properly configured in your Truffle configuration file (truffle.js)

3.4 验收测试智能合约

1）参考宠物商店的文章代码，在一个窗口启动一个ganache-cli 钱包。

duncanwang@ubuntu:~/work/name-age$ cd ..
duncanwang@ubuntu:~/work$ ganache-cli >>trace.log

2）编译智能合约

然后启动另外一个窗口命令行，输入一下命令。

duncanwang@ubuntu:~/work/name-age$ truffle compile

Compiling ./contracts/InfoContract.sol...

Compiling ./contracts/Migrations.sol...

Writing artifacts to ./build/contracts

3）智能合约验收命令。

测试成功的提示说明：

duncanwang@ubuntu:~/work/name-age$ truffle test

Using network 'development'.

Compiling ./contracts/InfoContract.sol...

Compiling ./test/TestInfoContract.sol...

Compiling truffle/Assert.sol...

Compiling truffle/DeployedAddresses.sol...

Compilation warnings encountered:

/home/duncanwang/work/name-age/test/TestInfoContract.sol:12:4: Warning: No visibility specified. Defaulting to "public".

    function testInfo() {

   ^ (Relevant source part starts here and spans across multiple lines).

  TestInfoContract

    ✓ testInfo (838ms)

  1 passing (5s)

3.5 完成前端页面

完成以下2个文件的修改更新和上传。

1） index.html

把宠物商店的index.html的代码删除，替换为本文需要的框架代码。

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <meta name="viewport" content="width=device-width, initial-scale=1.0"> 

   <meta http-equiv="X-UA-Compatible" content="ie=edge">

    <title>First Truffle DApp Demo</title>

    <link rel="stylesheet" type="text/css" href="main.css">

</head>

<body>

    <div class="container">

        <h1> First Truffle DApp Demo</h1>

        <h2 id="info"></h2>

        <img id="loader" src="https://loading.io/spinners/double-ring/lg.double-ring-spinner.gif">

        <label for="name" class="col-lg-2 control-label">姓名：</label>

        <input id="name" type="text">

        <label for="name" class="col-lg-2 control-label">年龄：</label>

        <input id="age" type="text">

        <button id="button">更新</button>

    </div>

    <script src="http://libs.baidu.com/jquery/2.1.1/jquery.min.js"></script>

    <script src="js/web3.min.js"></script>

    <script src="js/truffle-contract.js"></script>

    <script src="js/app.js"></script>

2） app.js

然后修改app.js的代码，完成智能合约的执行和调用作用。

App = {

  web3Provider: null,

  contracts: {}, 

 init: function() {

    return App.initWeb3(); 

 },

/*加载web3*/

  initWeb3: function() {

    if (typeof web3 !== 'undefined') {

         App.web3Provider = web3.currentProvider

         web3 = new Web3(App.web3Provider);

     } else {

         App.web3Provider = new Web3.providers.HttpProvider("http://localhost:9545") 

        web3 = new Web3(App.web3Provider);

     }

     return App.initContract();

  },

/*初始化合约，获取合约，不需要使用at()的方式；

  显示合约的姓名和年龄信息*/

  initContract: function() {

    $.getJSON('InfoContract.json', function(data){

      App.contracts.InfoContract = TruffleContract(data); 

     App.contracts.InfoContract.setProvider(App.web3Provider);

      App.getInfo();

      App.watchChanged();

    });

    App.bindEvents();

  },  

getInfo: function() {

    App.contracts.InfoContract.deployed().then(function(instance) {

      return instance.getInfo.call();

    }).then(function(result) { 

     $("#loader").hide();

      $("#info").html(result[0]+' ('+result[1]+' years old)'); 

     console.log(result);

    }).catch(function(err) {

      console.error(err); 

   });

  },

/*点击按钮更新姓名和年龄，则需要更新到智能合约上*/

  bindEvents: function() {

    $("#button").click(function() { 

       $("#loader").show();

        App.contracts.InfoContract.deployed().then(function(instance) {

          return instance.setInfo($("#name").val(), $("#age").val(), {gas: 500000}); 

       }).then(function(result) {

          return App.getInfo();

        } ).catch(function(err) {

          console.error(err);

        }); 

     });

  }, 

 watchChanged: function() { 

   App.contracts.InfoContract.deployed().then(function(instance) { 

     var infoEvent = instance.Instructor(); 

     return infoEvent.watch(function(err, result) {

        $("#loader").hide();

        $("#info").html(result.args.name +' ('+ result.args.age +' years old)'); 

     }); 

   });

  }

  }

$(function(){  

$(window).load(function() {

      App.init();

  });

});

3.6 测试验收前端和合约交互代码

1）部署合约

合约部署成功。

duncanwang@ubuntu:~/work/name-age$ truffle migrate

Using network 'development'.

Running migration: 1_initial_migration.js

  Deploying Migrations...

  ... 0x5b3cd41a7fa7c58361172ac797412469a10edfbe721d8d81988f19282c9cb6e4

  Migrations: 0x92b6ecd23aa98fad36926c12ec701f9aaa0933f4

Saving successful migration to network...

  ... 0x826fcd5b72b48435bf4f9941305727e52b0b7290631ba7b39f642027b1ee6947

Saving artifacts...

Running migration: 2_info_contract.js

  Deploying InfoContract...

  ... 0x9943dd7b90207bd9fd1e85524d1d0227f18a92269d73f5a2141cb71c22dda1e9

  InfoContract: 0x191391c710e1b632e40b4f2267dbc0f3bdb2bed4

Saving successful migration to network...

  ... 0x7e11f6e32585524e338e73439e4026c7c766625e5d23d56a4c90f8a11e5001ed

Saving artifacts...

2）安装并启动lite-server

1] 安装lite-server

【定义】lite-server 是轻量级的，仅适用于开发的 node 服务器，它仅支持 web app。它能够为你打开浏览器, 当你的html或是JavaScript文件变化时，它会识别到并自动帮你刷新浏览器, 还能使用套接字自动注入变化的CSS, 当路由没有被找到时，它将自动后退页面。

参考：如何在WINDOWS环境下搭建以太坊开发环境（https://www.jianshu.com/p/683ea7d62a39），完成MetaMask和liteServer的安装。

duncanwang@ubuntu:~/work/name-age$ npm install lite-server --save-dev

成功安装的输出结果如下：

npm WARN pet-shop@1.0.0 No description

npm WARN pet-shop@1.0.0 No repository field.

npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.4 (node_modules/fsevents):

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.4: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"ia32"})

+ lite-server@2.4.0

added 342 packages from 273 contributors in 56.82s

**2] 在新的窗口完成lite-server的启动。**

duncanwang@ubuntu:~/work/name-age$ npm run dev

> pet-shop@1.0.0 dev /home/duncanwang/work/name-age

> lite-server

** browser-sync config **

{ injectChanges: false,

  files: [ './**/*.{html,htm,css,js}' ],

  watchOptions: { ignored: 'node_modules' },

  server:

    { baseDir: [ './src', './build/contracts' ],

     middleware: [ [Function], [Function] ] } }

[Browsersync] Access URLs:

 --------------------------------------

       Local: http://localhost:3000

    External: http://10.225.18.149:3000

 --------------------------------------

          UI: http://localhost:3001

 UI External: http://localhost:3001

 --------------------------------------

[Browsersync] Serving files from: ./src

[Browsersync] Serving files from: ./build/contracts

[Browsersync] Watching files...

3）打开主页

输入lite-server提示的主页地址：http://10.225.18.149:3000

可以看到页面输出信息。