Truffle3.0集成NodeJS并完全跑通（附详细实例，可能的错误）

Truffle3.0集成NodeJS并完全跑通（附详细实例，可能的错误）
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 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

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 --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
└─┬ [email protected]
├─┬ [email protected]
│ ├── [email protected]
│ ├── [email protected]
│ └─┬ [email protected]
│ ├── [email protected] deduped
│ └─┬ [email protected]
│ └── [email protected]

├── [email protected]
├─┬ [email protected]
│ └── [email protected]
└─┬ [email protected]
└── [email protected] (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
[email protected] /Users/TryBlockchain/develop/blockchain_workspace/truffle3
└─┬ [email protected]
├─┬ [email protected]
│ ├── [email protected]
│ ├── [email protected]
│ └─┬ [email protected]
│ ├── [email protected] deduped
│ └─┬ [email protected]

│ └── [email protected]
├─┬ [email protected]
│ └─┬ [email protected]
│ ├── [email protected] (git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2)
│ ├── [email protected] deduped
│ ├── [email protected] deduped
│ ├── [email protected]
│ └── [email protected] deduped
├─┬ [email protected]
│ └── [email protected]
└─┬ [email protected]
├── [email protected] (git+https://github.com/debris/bignumber.js.git#94d7146671b9719e00a09c29b01a691bc85048c2)
├── [email protected]
├── [email protected]
└── [email protected]
安装NodeJS中用到的Truffle运行时需要的web3环境
$ npm install web3
- [email protected] node_modules/web3/node_modules/bignumber.js
[email protected] /Users/TryBlockchain/develop/blockchain_workspace/truffle3
└── [email protected]
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. (/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”: “0x606060405234610000575b6101ff806100196000396000f300606060405263ffffffff60e060020a60003504166326121ff0811461002f578063e2179b8e146100bc575b610000565b346100005761003c610149565b604080516020808252835181830152835191928392908301918501908083838215610082575b80518252602083111561008257601f199092019160209182019101610062565b505050905090810190601f1680156100ae5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b346100005761003c61018e565b604080516020808252835181830152835191928392908301918501908083838215610082575b80518252602083111561008257601f199092019160209182019101610062565b505050905090810190601f1680156100ae5780820380516001836020036101000a031916815260200191505b509250505060405180910390f35b604080516020818101835260009091528151808301909252600a82527f6d6574686f642066282900000000000000000000000000000000000000000000908201525b90565b604080516020818101835260009091528151808301909252600a82527f6d6574686f642067282900000000000000000000000000000000000000000000908201525b905600a165627a7a72305820c238bd4de6aa330fcc88946b9948bc265c7ac1408dc5c8b7ee6e648413ae540f0029”,
“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. (/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 address3。

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

1. 移植详解 ↩

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 ↩

合约交互详解 ↩