这篇文章的内容紧接着上章的内容，上一篇讲了truffle合约部署的基本操作，文章最后讲了通过console来调用部署成功的合约中的方法，之所以truffle console能够直接调用合约中的方式，是因为truffle console默认集成了web3。如果想在NodeJS环境使用Truffle合约，就要手动集成这两个模块。
集成NodeJS
1.首先需要安装npm包管理器，这里就不讲安装过程，如果已经安装过最好把npm更新到最新版本，不然在后面的操作中可能会报错，以下就是我在操作过程中遇到的一个错误。
var BigNumber = (new Web3()).toBigNumber(0).constructor;
^
TypeError: (intermediate value).toBigNumber is not a function
2.创建工程的npm包管理器，这里我们还是以上一个项目为例，进入项目所在的目录，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 ` afterwards to install a package and
save it as a dependency in the package.json file.
Press ^C at any time to quit.
package name: (truffletest) truffletest //回车或输入括号内的包名
version: (1.0.0) 1.0.0 //同上
license: (ISC) //同上
About to write to /Users/cyril/Desktop/truffleTest/package.json:
{
"name": "truffletest",
"version": "1.0.0",
"description": "truffle with nodejs",
"main": "main.js",
"directories": {
"test": "test"
},
"scripts": {
"test": "truffletest"
},
"repository": {
"type": "git",
"url": "main.js"
},
"keywords": [
"truffletest"
],
"author": "cyril",
"license": "ISC",
"dependencies": {
"truffle-contract": "^3.0.6",
"web3": "^1.0.0-beta2"
}
}
Is this OK? (yes) yes //同前面的操作
这个时候项目会生成package.json和package-lock.json同时会添加node-modules相关的库依赖，生成的这些文件没必要去修改
项目结构如下：
安装
NodeJS中用到的Truffle合约抽象层运行环境
truffle-contract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。
$ npm install truffle-contract
npm notice created a lockfile as package-lock.json. You should commit this file.
+ [email protected]
added 24 packages from 18 contributors and audited 25 packages in 13.15s
found 0 vulnerabilities
安装NodeJS中用到的Truffle运行时需要的web3环境
$ npm install web3
npm WARN deprecated [email protected]: This version has faulty dependecy links.
+ [email protected]
added 1 package from 1 contributor and audited 26 packages in 1.752s
found 0 vulnerabilities
测试合约
这里就用前面的Test.sol和Greeter.sol，部署流程就不讲了，在项目根目录下创建main.js，内容大体结构如下
//引入依赖，并初始化一个实例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*/);//合约的元数据
//设置连接
Test.setProvider(provider);
//设置默认地址
Test.defaults({
from : "0x299127d72e28cb92d09f856aaedeb139d1e7e74a"
});
//函数调用
//TODO
我们拿Test举个例子：
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({
"contractName": "Test",
"abi": [
{
"constant": true,
"inputs": [],
"name": "f",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "pure",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "g",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "pure",
"type": "function"
}
],
"networks": {
"1536568575803": {
"events": {},
"links": {},
"address": "0x57fec0a6d60ce7a133bbc6f7ac64f99a7b97425f",
"transactionHash": "0x84463c7b8bce644a4df200ed1afdb3714514696cb32eef443854ca2dc2e56a70"
},
"1536655141628": {
"events": {},
"links": {},
"address": "0x03873f72987988a143d514f43a6c548fe8d252b9",
"transactionHash": "0xd3b7577fb5aae6a5950c0b2e04e1211f26ce487dda065d264bf6c61e2b453983"
}
},
"schemaVersion": "2.0.1",
"updatedAt": "2018-09-11T09:04:16.743Z"
});
Test.setProvider(provider);
//随便从testrpc提供的地址中拷贝一个
Test.defaults({
from: "0x807b0d9ffc27ecdc481bd1fc84fd3d4fb054c324"
});
//调用合约方法
var instance;
Test.deployed().then(function (func) {
instance = func;
return instance.f.call();
}).then(function (value) {
console.log(value);
return instance.g.call();
}).then(function (value) {
console.log(value);
});
注意：
1.最好原封不动的把json文件的内容拷贝过来，为了节约篇幅，我就只粘贴了部分，虽然不影响正常测试，但可能遇到下面的错误：node_modules/truffle->contract/node_modules/web3/lib/web3/contract.js:56 contract.abi.filter(function (json) { ^ TypeError: Cannot read property 'filter' of undefined2.必须设置默认账户，
truffle-contract框架默认没有读取coinbase的默认地址，所以需要主动设置，不然会报如下错误：(node:26922) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): Error: invalid address
运行main.js
运行main.js，然后报了如下错：
$ node main.js
module.js:487
throw err;
^
Error: Cannot find module 'web3-requestManager'
这个问题就是我开篇说的一定要注意运行环境的版本，这个问题是因为package.json中依赖的web3版本是^1.0.0-beta2，这个问题可以通过安装依赖解决
$ npm install ethereum/web3.js
+ [email protected]
added 4 packages from 4 contributors, updated 1 package and audited 32 packages in 58.834s
found 0 vulnerabilities
再次查看package.json中的web3版本已经变成了github:ethereum/web3.js，然后再次运行main.js
$ node main.js
method f()
method g()
输出结果跟上篇内容的一样，也在预料之中。不论是合约中的f()方法还是g()方法，都不会改写区块链状态，使用instance.f.call()调用；而对于一个会改写区块链状态的函数f()，使用instance.f()调用，我们在以Greeter.sol为例来演示一下
下面的代码依然是放在main.js里
var Web3 = require('web3');
var contract = require("truffle-contract");
var provider = new Web3.providers.HttpProvider("http://localhost:8545");
var Greeter = contract({
"contractName": "Greeter",
"abi": [
{
"inputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "constructor"
},
{
"constant": true,
"inputs": [],
"name": "greet",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_newgreeting",
"type": "string"
}
],
"name": "setGreeting",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [],
"name": "kill",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
}
],
"networks": {
"1536568575803": {
"events": {},
"links": {},
"address": "0x4cf91392df7740176d74f63faf9991ec838a6473",
"transactionHash": "0x33b9776384f25342d51799970744b44dcfedf55a36093d55a72c5323dcbc8cf5"
},
"1536655141628": {
"events": {},
"links": {},
"address": "0x2eb0113712145ffb42889c9421a6881e864ff2b4",
"transactionHash": "0x748948df55b1597223d54cc6184d7a43ac47a04a559fafd9eb49e3c02c1abe98"
}
},
"schemaVersion": "2.0.1",
"updatedAt": "2018-09-11T09:04:16.744Z"
});
Greeter.setProvider(provider);
Greeter.defaults({
from: "0xd10e318f0ef3e74c6e75e0827b840b2d00a49af5"
});
var ins;
Greeter.deployed().then(function (value) {
ins = value;
return ins.setGreeting("hello");
}).then(function (value) {
console.log(value);
return ins.greet.call();
}).then(function (value) {
console.log(value);
});
运行
$ node main.js
{ tx: '0x887d1043feb6f1e65bd90c71840b6b8fe8b2eea6ac19ad82dbd3c61c8eccae4c',
receipt:
{ transactionHash: '0x887d1043feb6f1e65bd90c71840b6b8fe8b2eea6ac19ad82dbd3c61c8eccae4c',
transactionIndex: 0,
blockHash: '0x323b5d22dbea9f4d7c1e70da5a0dc2b4b96f453afd6a3ae80c989470804c6562',
blockNumber: 17,
gasUsed: 33090,
cumulativeGasUsed: 33090,
contractAddress: null,
logs: [],
status: 1 },
logs: [] }
//greet()方法输出内容
hello
因为ins.setGreeting ()方法会改变区块链状态，所以需要消耗gas，同时在调用的时候返回对应的交易状态结果。