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最近研究了下Koa2框架，喜爱其中间件的思想。但是发现实在是太简洁了，只有基本功能，虽然可以方便搭各种服务，但是离可以适应快速开发的网站框架还是有点距离。于是参考Rails的大致框架搭建了个网站框架kails, 配合postgres和redis, 实现了MVC架构，前端webpack，react前后端同构等网站开发基本框架。本文主要介绍kails搭建中的各种技术栈和思想。
本文首发于Blog of Embbnux, 转载请注明原文出处:
https://www.embbnux.com/2016/09/04/kails_with_koa2_like_ruby_on_rails/
koa来源于express的主创团队，主要利用es6的generators特性实现了基于中间件思想的新的框架，但是和express不同，koa并不想express一样提供一个可以满足基本网站开发的框架，而更像是一个基本功能模块，要满足网站还是需要自己引入很多功能模块。所以根据选型大的不同，有各种迥异的koa项目，kails由名字也可以看出是一个类似Ruby on Rails的koa项目。
├── app.js
├── assets
│ ├── images
│ ├── javascripts
│ └── stylesheets
├── config
│ ├── config.js
│ ├── development.js
│ ├── test.js
│ ├── production.js
│ └── webpack.config.js
│ ├── webpack
├── routes
├── models
├── controllers
├── views
├── db
│ └── migrations
├── helpers
├── index.js
├── package.json
├── public
└── testkails选用的是koa2作为核心框架，koa2使用es7的async和await等功能，node在开启harmony后还是不能运行，所以要使用babel等语言转化工具进行支持:
babel6配置文件:
.babelrc:
{
"presets": [
"es2015",
"stage-0",
"react"
]
}在入口使用babel加载整个功能，使支持es6
require(‘babel-core/register‘)
require(‘babel-polyfill‘)
require(‘./app.js‘)app.js是核心文件，koa2的中间件的引入和使用主要在这里，这里会引入各种中间件和配置, 具体详细功能介绍后面会慢慢涉及到。
下面是部分内容，具体内容见github上仓库
import Koa from ‘koa‘
import session from ‘koa-generic-session‘
import csrf from ‘koa-csrf‘
import views from ‘koa-views‘
import convert from ‘koa-convert‘
import json from ‘koa-json‘
import bodyParser from ‘koa-bodyparser‘
import config from ‘./config/config‘
import router from ‘./routes/index‘
import koaRedis from ‘koa-redis‘
import models from ‘./models/index‘
const redisStore = koaRedis({
url: config.redisUrl
})
const app = new Koa()
app.keys = [config.secretKeyBase]
app.use(convert(session({
store: redisStore,
prefix: ‘kails:sess:‘,
key: ‘kails.sid‘
})))
app.use(bodyParser())
app.use(convert(json()))
app.use(convert(logger()))
// not serve static when deploy
if(config.serveStatic){
app.use(convert(require(‘koa-static‘)(__dirname + ‘/public‘)))
}
//views with pug
app.use(views(‘./views‘, { extension: ‘pug‘ }))
// csrf
app.use(convert(csrf()))
app.use(router.routes(), router.allowedMethods())
app.listen(config.port)
export default app
网站架构还是以mvc分层多见和实用，能满足很多场景的网站开发了，逻辑再复杂点可以再加个服务层，这里基于koa-router进行路由的分发，从而实行MVC分层
路由的配置主要由routes/index.js文件去自动加载其目录下的其它文件，每个文件负责相应的路由头下的路由分发，如下
routes/index.js
import fs from ‘fs‘
import path from ‘path‘
import Router from ‘koa-router‘
const basename = path.basename(module.filename)
const router = Router()
fs
.readdirSync(__dirname)
.filter(function(file) {
return (file.indexOf(‘.‘) !== 0) && (file !== basename) && (file.slice(-3) === ‘.js‘)
})
.forEach(function(file) {
let route = require(path.join(__dirname, file))
router.use(route.routes(), route.allowedMethods())
})
export default router
路由文件主要负责把相应的请求分发到对应controller中，路由主要采用restful分格。
routes/articles.js
import Router from ‘koa-router‘
import articles from ‘../controllers/articles‘
const router = Router({
prefix: ‘/articles‘
})
router.get(‘/new‘, articles.checkLogin, articles.newArticle)
router.get(‘/:id‘, articles.show)
router.put(‘/:id‘, articles.checkLogin, articles.checkArticleOwner, articles.checkParamsBody, articles.update)
router.get(‘/:id/edit‘, articles.checkLogin, articles.checkArticleOwner, articles.edit)
router.post(‘/‘, articles.checkLogin, articles.checkParamsBody, articles.create)
// for require auto in index.js
module.exports = routermodel层这里基于Sequelize实现orm对接底层数据库postgres, 利用sequelize-cli实现数据库的迁移功能.
例子:
user.js
import bcrypt from ‘bcrypt‘
export default function(sequelize, DataTypes) {
const User = sequelize.define(‘User‘, {
id: {
type: DataTypes.INTEGER,
primaryKey: true,
autoIncrement: true
},
name: {
type: DataTypes.STRING,
validate: {
notEmpty: true,
len: [1, 50]
}
},
email: {
type: DataTypes.STRING,
validate: {
notEmpty: true,
isEmail: true
}
},
passwordDigest: {
type: DataTypes.STRING,
field: ‘password_digest‘,
validate: {
notEmpty: true,
len: [8, 128]
}
},
password: {
type: DataTypes.VIRTUAL,
allowNull: false,
validate: {
notEmpty: true
}
},
passwordConfirmation: {
type: DataTypes.VIRTUAL
}
},{
underscored: true,
tableName: ‘users‘,
indexes: [{ unique: true, fields: [‘email‘] }],
classMethods: {
associate: function(models) {
User.hasMany(models.Article, { foreignKey: ‘user_id‘ })
}
},
instanceMethods: {
authenticate: function(value) {
if (bcrypt.compareSync(value, this.passwordDigest)){
return this
}
else{
return false
}
}
}
})
function hasSecurePassword(user, options, callback) {
if (user.password != user.passwordConfirmation) {
throw new Error(‘Password confirmation doesn\‘t match Password‘)
}
bcrypt.hash(user.get(‘password‘), 10, function(err, hash) {
if (err) return callback(err)
user.set(‘passwordDigest‘, hash)
return callback(null, options)
})
}
User.beforeCreate(function(user, options, callback) {
user.email = user.email.toLowerCase()
if (user.password){
hasSecurePassword(user, options, callback)
}
else{
return callback(null, options)
}
})
User.beforeUpdate(function(user, options, callback) {
user.email = user.email.toLowerCase()
if (user.password){
hasSecurePassword(user, options, callback)
}
else{
return callback(null, options)
}
})
return User
}
网站开发测试与部署等都会有不同的环境，也就需要不同的配置，这里我主要分了development,test和production环境，使用时用自动基于NODE_ENV变量加载不同的环境配置。
实现代码:
config/config.js
var _ = require(‘lodash‘);
var development = require(‘./development‘);
var test = require(‘./test‘);
var production = require(‘./production‘);
var env = process.env.NODE_ENV || ‘development‘;
var configs = {
development: development,
test: test,
production: production
};
var defaultConfig = {
env: env
};
var config = _.merge(defaultConfig, configs[env]);
module.exports = config;生产环境的配置:
config/production.js
const port = Number.parseInt(process.env.PORT, 10) || 5000
module.exports = {
port: port,
hostName: process.env.HOST_NAME_PRO,
serveStatic: process.env.SERVE_STATIC_PRO || false,
assetHost: process.env.ASSET_HOST_PRO,
redisUrl: process.env.REDIS_URL_PRO,
secretKeyBase: process.env.SECRET_KEY_BASE
};
koa是以中间件思想构建的，自然代码中离不开中间件，这里介绍几个中间件的应用
currentUser用于获取当前登录用户，在网站用户系统上中具有重要的重要
app.use(async (ctx, next) => {
let currentUser = null
if(ctx.session.userId){
currentUser = await models.User.findById(ctx.session.userId)
}
ctx.state = {
currentUser: currentUser,
isUserSignIn: (currentUser != null)
}
await next()
})这样在以后的中间件中就可以通过ctx.state.currentUser得到当前用户
比如article的controller里的edit和update,都需要找到当前的article对象，也需要验证权限，而且是一样的，为了避免代码重复，这里也可以用中间件
controllers/articles.js
async function edit(ctx, next) {
const locals = {
title: ‘编辑‘,
nav: ‘article‘
}
await ctx.render(‘articles/edit‘, locals)
}
async function update(ctx, next) {
let article = ctx.state.article
article = await article.update(ctx.state.articleParams)
ctx.redirect(‘/articles/‘ + article.id)
return
}
async function checkLogin(ctx, next) {
if(!ctx.state.isUserSignIn){
ctx.status = 302
ctx.redirect(‘/‘)
return
}
await next()
}
async function checkArticleOwner(ctx, next) {
const currentUser = ctx.state.currentUser
const article = await models.Article.findOne({
where: {
id: ctx.params.id,
userId: currentUser.id
}
})
if(article == null){
ctx.redirect(‘/‘)
return
}
ctx.state.article = article
await next()
}在路由中应用中间件
router.put(‘/:id‘, articles.checkLogin, articles.checkArticleOwner, articles.update)
router.get(‘/:id/edit‘, articles.checkLogin, articles.checkArticleOwner, articles.edit)这样就相当于实现了rails的before_action的功能
在没实现前后端分离前，工程代码中肯定还是少不了前端代码，现在在webpack是前端模块化编程比较出名的工具，这里用它来做rails中assets pipeline的功能，这里介绍下基本的配置。
config/webpack/base.js
var webpack = require(‘webpack‘);
var path = require(‘path‘);
var publicPath = path.resolve(__dirname, ‘../‘, ‘../‘, ‘public‘, ‘assets‘);
var ManifestPlugin = require(‘webpack-manifest-plugin‘);
var assetHost = require(‘../config‘).assetHost;
var ExtractTextPlugin = require(‘extract-text-webpack-plugin‘);
module.exports = {
context: path.resolve(__dirname, ‘../‘, ‘../‘),
entry: {
application: ‘./assets/javascripts/application.js‘,
articles: ‘./assets/javascripts/articles.js‘,
editor: ‘./assets/javascripts/editor.js‘
},
module: {
loaders: [{
test: /\.jsx?$/,
exclude: /node_modules/,
loader: [‘babel-loader‘],
query: {
presets: [‘react‘, ‘es2015‘]
}
},{
test: /\.coffee$/,
exclude: /node_modules/,
loader: ‘coffee-loader‘
},
{
test: /\.(woff|woff2|eot|ttf|otf)\??.*$/,
loader: ‘url-loader?limit=8192&name=[name].[ext]‘
},
{
test: /\.(jpe?g|png|gif|svg)\??.*$/,
loader: ‘url-loader?limit=8192&name=[name].[ext]‘
},
{
test: /\.css$/,
loader: ExtractTextPlugin.extract("style-loader", "css-loader")
},
{
test: /\.scss$/,
loader: ExtractTextPlugin.extract(‘style‘, ‘css!sass‘)
}]
},
resolve: {
extensions: [‘‘, ‘.js‘, ‘.jsx‘, ‘.coffee‘, ‘.json‘]
},
output: {
path: publicPath,
publicPath: assetHost + ‘/assets/‘,
filename: ‘[name]_bundle.js‘
},
plugins: [
new webpack.ProvidePlugin({
$: ‘jquery‘,
jQuery: ‘jquery‘
}),
// new webpack.HotModuleReplacementPlugin(),
new ManifestPlugin({
fileName: ‘kails_manifest.json‘
})
]
};node的好处是v8引擎只要是js就可以跑，所以想react的渲染dom功能也可以在后端渲染，有利用实现react的前后端同构，利于seo，对用户首屏内容也更加友好。
在前端跑react我就不说了，这里讲下在koa里面怎么实现的:
import React from ‘react‘
import { renderToString } from ‘react-dom/server‘
async function index(ctx, next) {
const prerenderHtml = await renderToString(
<Articles articles={ articles } />
)
}测试和lint自然是开发过程中工程化不可缺少的一部分，这里kails的测试采用mocha，lint使用eslint
.eslintrc:
{
"parser": "babel-eslint",
"root": true,
"rules": {
"new-cap": 0,
"strict": 0,
"no-underscore-dangle": 0,
"no-use-before-define": 1,
"eol-last": 1,
"indent": [2, 2, { "SwitchCase": 0 }],
"quotes": [2, "single"],
"linebreak-style": [2, "unix"],
"semi": [1, "never"],
"no-console": 1,
"no-unused-vars": [1, {
"argsIgnorePattern": "_",
"varsIgnorePattern": "^debug$|^assert$|^withTransaction$"
}]
},
"env": {
"browser": true,
"es6": true,
"node": true,
"mocha": true
},
"extends": "eslint:recommended"
}用过rails的，应该都知道rails有个rails console，可以已命令行的形式进入网站的环境,很是方便，这里基于repl实现:
if (process.argv[2] && process.argv[2][0] == ‘c‘) {
const repl = require(‘repl‘)
global.models = models
repl.start({
prompt: ‘> ‘,
useGlobal: true
}).on(‘exit‘, () => { process.exit() })
}
else {
app.listen(config.port)
}开发完自然是要部署到线上，这里用pm2来管理：
NODE_ENV=production ./node_modules/.bin/pm2 start index.js -i 2 --name "kails" --max-memory-restart 300M --merge-logs --log-date-format="YYYY-MM-DD HH:mm Z" --output="log/production.log"有些常用命令参数较多，也比较长，可以使用npm scripts里为这些命令做一些别名
{
"scripts": {
"console": "node index.js console",
"start": "./node_modules/.bin/nodemon index.js & node_modules/.bin/webpack --config config/webpack.config.js --progress --colors --watch",
"app": "node index.js",
"pm2": "NODE_ENV=production ./node_modules/.bin/pm2 start index.js -i 2 --name \"kails\" --max-memory-restart 300M --merge-logs --log-date-format=\"YYYY-MM-DD HH:mm Z\" --output=\"log/production.log\"",
"pm2:restart": "NODE_ENV=production ./node_modules/.bin/pm2 restart \"kails\"",
"pm2:stop": "NODE_ENV=production ./node_modules/.bin/pm2 stop \"kails\"",
"pm2:monit": "NODE_ENV=production ./node_modules/.bin/pm2 monit \"kails\"",
"pm2:logs": "NODE_ENV=production ./node_modules/.bin/pm2 logs \"kails\"",
"test": "NODE_ENV=test ./node_modules/.bin/mocha --compilers js:babel-core/register --recursive --harmony --require babel-polyfill",
"assets_build": "node_modules/.bin/webpack --config config/webpack.config.js",
"assets_compile": "NODE_ENV=production node_modules/.bin/webpack --config config/webpack.config.js -p",
"webpack_dev": "node_modules/.bin/webpack --config config/webpack.config.js --progress --colors --watch",
"lint": "eslint . --ext .js",
"db:migrate": "node_modules/.bin/sequelize db:migrate",
"db:rollback": "node_modules/.bin/sequelize db:migrate:undo",
"create:migration": "node_modules/.bin/sequelize migration:create"
}
}这样就会多出这些命令:
npm install
npm run db:migrate
NODE_ENV=test npm run db:migrate
# run for development, it start app and webpack dev server
npm run start
# run the app
npm run app
# run the lint
npm run lint
# run test
npm run test
# deploy
npm run assets_compile
NODE_ENV=production npm run db:migrate
npm run pm2目前kails实现了基本的博客功能，有基本的权限验证，以及markdown编辑等功能.
现在目前能想到更进一步的:
- 性能优化，加快响应速度
- Dockerfile简化部署
- 线上代码预编译
欢迎pull request : https://github.com/embbnux/kails
[Kails] 一个基于 Koa2 构建的类似于 Rails 的 nodejs 开源项目
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原文地址：http://blog.csdn.net/embbnux/article/details/52444567
