升级到Truffle3.0

如果之前安装的是Truffle2.0版本，需要主动升级到Truffle3.0，两者的语法变化有点大。

由于Truffle是一个命令行工具，需要更新全局空间安装的Truffle。

$ sudo npm update -g truffle

注意需要root权限运行命令，否则可能会报错无足够的访问权限，导致升级失败。

安装成功后，可以通过版本命令查看当前的版本，如出现下述类似字样说明升级成功：

$ truffle version
Truffle v3.1.2

初始化工程

使用Truffle3.0初始化工程

我们创建一个新工程目录，并在truffle3目录内初始化Truffle框架。

$ mkdir truffle3 && cd truffle3
$ truffle init
Downloading project...
Project initialized.

  Documentation: http://truffleframework.com/docs

Commands:

  Compile: truffle compile

  Migrate: truffle migrate
  Test:    truffle test

我们创建了一个新工程目录truffle3，进入到这个目录，使用truffle init命令，初始化了一个全新的Truffle 3.0的工程，工程目录如下：

truffle3-project.jpg

集成NodeJS

truffle console命令会默认集成web3，合约抽象层。如果想要在自已的NodeJS环境使用Truffle合约，就要手动集成这两个模块。在集成前，我们需要创建工程的npm包管理环境，首先进入truffle3工程目录，使用npm init来初始化工程的npm包管理环境：

$ npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help json` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg> --save` afterwards to install a package and
save it as a dependency in the package.json file.


Press ^C at any time to quit.
name: (truffle3) TruffleForTest
Sorry, name can no longer contain capital letters.
name: (truffle3) truffle3
version: (1.0.0) 1.0.0
description: This is a sample project for integrate truffle 3.0 with nodejs.
entry point: (truffle.js) main.js
test command: truffle3
git repository:main.js
keywords: truffle3.0
author: TryBlockchain
license: (ISC)
About to write to /Users/TryBlockchain/develop/blockchain_workspace/truffle3/package.json:

{
  "name": "truffle3",
  "version": "1.0.0",
  "description": "This is a sample project for integrate truffle 3.0 with nodejs.",

  "main": "main.js",
  "directories": {
    "test": "test"
  },
  "scripts": {
    "test": "truffle3"
  },
  "keywords": [
    "truffle3.0"
  ],
  "author": "TryBlockchain",
  "license": "ISC"
}


Is this ok? (yes) yes

如果不进行npm init初始化，就进行后续模块安装，会报如下错误：

$ npm install truffle-contract
/Users/TryBlockchain
└─┬ truffle-contract@1.1.10
  ├─┬ ethjs-abi@0.1.9
  │ ├── bn.js@4.11.6
  │ ├── js-sha3@0.5.5
  │ └─┬ number-to-bn@1.7.0
  │   ├── bn.js@4.11.6  deduped
  │   └─┬ strip-hex-prefix@1.0.0
  │     └── is-hex-prefixed@1.0.0

  ├── truffle-blockchain-utils@0.0.1
  ├─┬ truffle-contract-schema@0.0.5
  │ └── crypto-js@3.1.9-1
  └─┬ web3@0.16.0
    └── bignumber.js@2.0.7  (git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2)

npm WARN enoent ENOENT: no such file or directory, open '/Users/TryBlockchain/package.json'
npm WARN TryBlockchain No description
npm WARN TryBlockchain No repository field.
npm WARN TryBlockchain No README data
npm WARN TryBlockchain No license field.

由于没有包管理环境，所以对package.json的包依赖写入会失败。报错npm WARN enoent ENOENT: no such file or directory, open '/Users/TryBlockchain/package.json'。要解决这个问题，需要使用npm init来初始化当前工程的包管理环境。

安装NodeJS中用到的Truffle合约抽象层运行环境

这个工具是Truffle提供的，用于在NodeJS和浏览器中集成Truffle的合约抽象运行环境^[1]。

$ npm install truffle-contract
truffle3@1.0.0 /Users/TryBlockchain/develop/blockchain_workspace/truffle3
└─┬ truffle-contract@1.1.10
  ├─┬ ethjs-abi@0.1.9
  │ ├── bn.js@4.11.6
  │ ├── js-sha3@0.5.5
  │ └─┬ number-to-bn@1.7.0
  │   ├── bn.js@4.11.6  deduped
  │   └─┬ strip-hex-prefix@1.0.0

  │     └── is-hex-prefixed@1.0.0
  ├─┬ truffle-blockchain-utils@0.0.1
  │ └─┬ web3@0.18.2
  │   ├── bignumber.js@2.0.7  (git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2)
  │   ├── crypto-js@3.1.8  deduped
  │   ├── utf8@2.1.2  deduped
  │   ├── xhr2@0.1.4
  │   └── xmlhttprequest@1.8.0  deduped
  ├─┬ truffle-contract-schema@0.0.5
  │ └── crypto-js@3.1.9-1
  └─┬ web3@0.16.0
    ├── bignumber.js@2.0.7  (git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2)
    ├── crypto-js@3.1.8
    ├── utf8@2.1.2
    └── xmlhttprequest@1.8.0

安装NodeJS中用到的Truffle运行时需要的web3环境

$ npm install web3
- bignumber.js@2.0.7 node_modules/web3/node_modules/bignumber.js
truffle3@1.0.0 /Users/TryBlockchain/develop/blockchain_workspace/truffle3
└── web3@0.18.2

我们使用npm install web3即可安装web3模块。如果没有集成web3环境，就跑相关的代码，可能会报下述错：

$ node main.js
/Users/TryBlockchain/develop/blockchain_workspace/truffle3/main/main.js:4
var provider = new Web3.providers.HttpProvider("http://localhost:8545");
                   ^

ReferenceError: Web3 is not defined
    at Object.<anonymous> (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/main/main.js:4:20)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_NodeJS:420:7)
    at startup (bootstrap_NodeJS:139:9)
    at bootstrap_NodeJS:535:3

创建自己的合约文件

新增加测试合约

在truffle3/contracts目录下创建测试合约文件Test.sol

pragma solidity ^0.4.4;

contract Test{
    function f() returns (string){
        return "method f()";
    }
    function g() returns (string){
        return "method g()";
    }
}

在上述代码中，我们提供两个函数，f()和g()。分别返回用于说明它们是哪个函数的返回结果的字符串说明。

增加deploy配置

修改migrations/2_deploy_contracts.js为如下：

var ConvertLib = artifacts.require("./ConvertLib.sol");
var MetaCoin = artifacts.require("./MetaCoin.sol");
var Test = artifacts.require("./Test.sol");

module.exports = function(deployer) {
  deployer.deploy(ConvertLib);
  deployer.link(ConvertLib, MetaCoin);
  deployer.deploy(MetaCoin);
  deployer.deploy(Test);
};

上述代码主要增加两行，一行为var Test = artifacts.require("./Test.sol");声明一个新的合约文件实例并命名为Test；增加的另一行内容deployer.deploy(Test);用于将Test进行部署。

编译合约

下面我们使用truffle migrate --reset来强制重编译并发布所有合约，由于合约移植是懒编译的，如果发现已经发布过，且发布的版本号没有变化就不会再发布，所以使用--reset。请务必弄清楚为何使用--reset再使用这个命令^[2]。运行truffle migrate前，需要确认节点处于运行状态。

$ truffle migrate --reset
Using network 'development'.

Running migration: 1_initial_migration.js

  Replacing Migrations...
  Migrations: 0xdc59c5de4e7b1dcf23f864425a704020e53666b5
Saving successful migration to network...
Saving artifacts...
Running migration: 2_deploy_contracts.js
  Replacing ConvertLib...
  ConvertLib: 0x19cf958fede2e0f082cbcf5629f1a1344b221bf3
  Linking ConvertLib to MetaCoin
  Replacing MetaCoin...
  MetaCoin: 0x39073d502491f57537f999584071691d19cf5f24
  Replacing Test...
  Test: 0x8ca770415902e5a64ef53062b5ba85626c3dd5dc
Saving successful migration to network...
Saving artifacts...

使用NodeJS集成Truffle3.0代码完整DEMO

var Web3 = require('web3');
var contract = require("truffle-contract");

var provider = new Web3.providers.HttpProvider("http://localhost:8545");

//使用truffle-contract包的contract()方法
//请务必使用你自己编译的.json文件内容
var Test = contract({
  "contract_name": "Test",
  "abi": [
    {
      "constant": false,
      "inputs": [],
      "name": "f",
      "outputs": [
        {
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "type": "function"
    },
    {
      "constant": false,
      "inputs": [],
      "name": "g",
      "outputs": [
        {
          "name": "",
          "type": "string"
        }
      ],
      "payable": false,
      "type": "function"
    }
  ],
  "unlinked_binary": "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",
  "networks": {
    "1489826524891": {
      "events": {},
      "links": {},
      "address": "0x9db90af99faa32ed14dccfb19326e917efac456b",
      "updated_at": 1489827968151
    }
  },
  "schema_version": "0.0.5",
  "updated_at": 1489827968151
});

Test.setProvider(provider);

//没有默认地址，会报错
//UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): Error: invalid address
//务必设置为自己的钱包地址，如果不知道，查看自己的客户端启动时，观察打印到控制台的地址
Test.defaults({
  from : "0x299127d72e28cb92d09f856aaedeb139d1e7e74a"
});


var instance;
Test.deployed().then(function(contractInstance) {
  instance = contractInstance;
  return instance.f.call();
}).then(function(result){
  console.log(result);
  return instance.g.call();
}).then(function(result){
  console.log(result);
});

集成示例详解

引入web3

要在NodeJS中使用Truffle，我们要先引入web3。

var Web3 = require('web3');
var provider = new Web3.providers.HttpProvider("http://localhost:8545");

//省略了无关代码
//合约初始化
var Test = contract(/*合约JSON*/);

//设置连接
Test.setProvider(provider);

在上例中，我们先通过var Web3 = require('web3');引入依赖，并初始化一个实例Web3，并为实例设置了HttpProvider。

truffle-contract的contract()方法

要在NodeJS初始化Truffle编译好的合约，要使用contract()方法。请将Truffle3.0编译后的.json文件，一般在build/contracts/Test.json。请将此文件的内容放入contract()的括号内。

var contract = require("truffle-contract");

//请使用使用Truffle3.0编译的.json文件内容
var Test = contract(/*参数是`JSON`对象，放入Truffle3.0生成的.json文件内容*/)

然后使用.deployed()或at(/*某个地址*/)来进行调用^[1]。

contract()引入的JSON定义有问题

如果引入的JSON数据有问题，你可能会看到下面的错误：

$ node main.js
/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/node_modules/web3/lib/web3/contract.js:56
    contract.abi.filter(function (json) {

                ^

TypeError: Cannot read property 'filter' of undefined
    at addFunctionsToContract (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/node_modules/web3/li
b/web3/contract.js:56:17)
    at ContractFactory.at (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/node_modules/web3/lib/we
b3/contract.js:255:5)
    at TruffleContract.Contract (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/contract.js:257:33
)
    at new TruffleContract (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/contract.js:572:25)
    at Function.at (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/node_modules/truffle-contract/contract.js:390:22)
    at Object.<anonymous> (/Users/TryBlockchain/develop/blockchain_workspace/truffle3/main/main.js:54:6)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)

如果你出现了上述报错，请再次确认是否原封不动的把合约编译后的.json文件的内容，复制进contract()的括号内的，不要加任何东西，因为.json文件内就是一个JSON对象。

默认帐户地址

truffle-contract框架默认没有读取coinbase的默认地址，所以需要按如下方式主动设置：

//没有默认地址，会报错
//UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): Error: invalid address
Test.defaults({
  from : "0x299127d72e28cb92d09f856aaedeb139d1e7e74a"
});

否则会报错UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): Error: invalid address^[3]。

语法注意

对于新的Truffle3.0语法，需要注意的是函数调用方式要遵循调用规则^[4]。对于一个不会改写区块链状态的f()函数，使用instance.f.call();；而对于一个会改写区块链状态的函数f()，使用instance.f()。底层在实现调用上，会使用不同gas计算方式。

var instance;
Test.deployed().then(function(contractInstance) {
  instance = contractInstance;
  return instance.f.call();
}).then(function(result){
  console.log(result);
  return instance.g.call();
}).then(function(result){
  console.log(result);
});

如果对于一个不会改写状态f()，使用instance.f()会返回对应的交易状态结果。

$ node main.js
{ tx: '0x2ac645310278d971e3911e8f880947105f582aa4eab3d3d66d14c95333391ac9',
  receipt:

   { transactionHash: '0x2ac645310278d971e3911e8f880947105f582aa4eab3d3d66d14c95333391ac9',
     transactionIndex: 0,
     blockHash: '0x69a6788032c7bef12d6d51bc045548fa9edb0665bb0fbcf9cf55d30f9744cd61',
     blockNumber: 29,
     gasUsed: 21803,
     cumulativeGasUsed: 21803,
     contractAddress: null,
     logs: [] },
  logs: [] }
{ tx: '0x65aa2c4da73ef5a17221c26e74b9b329bdc353856564f8d1f49c07f6dcd055ea',
  receipt:
   { transactionHash: '0x65aa2c4da73ef5a17221c26e74b9b329bdc353856564f8d1f49c07f6dcd055ea',
     transactionIndex: 0,
     blockHash: '0x837ec6a3df2cc4d9a8ccf8d77c14b88a13b0053a5149a74c1a984fe88a70eaa8',
     blockNumber: 30,
     gasUsed: 21825,
     cumulativeGasUsed: 21825,
     contractAddress: null,
     logs: [] },
  logs: [] }

关于作者

专注基于以太坊的相关区块链技术，了解以太坊，Solidity，Truffle。
博客：http://me.tryblockchain.org

1. Truffle contract的github地址及文档： https://github.com/trufflesuite/truffle-contract ↩ ↩

2. 5. 移植详解 ↩

3. 关于invalid address的报错，http://ethereum.stackexchange.com/questions/12957/truffle-invalid-address 报这个错的可能情况： http://www.bullraider.com/ethereum/tutorials/342-understanding-invalid-address-error-in-dapps-or-geth-console ↩

4. 合约交互详解 ↩