把koa2扩展成一个完备服务端api开发框架

npm init

npm install koa -save

const Koa = require('koa')
const app = new Koa() 
app.use(async (ctx, next) => { 
	await next() 
	ctx.response.type = 'text/html' ctx.response.body = '<h1>Hello koa!</h1>'

}) app.listen(3000, () => { console.log('server is running at http://localhost:3000')
})

npm i babel-core  babel-polyfill babel-preset-env babel-preset-es2015  babel-preset-stage-0  -S 

require("babel-core/register")({  
    presets: ['env', 'stage-0']
});
require("babel-polyfill"); 

// 示例:载入 bodyparser中间件
  	app.use(bodyParser())

module.exports = () => {
  function render(json) {
      this.set("Content-Type", "application/json")
      this.body = JSON.stringify(json)
  }
  return async (ctx, next) => {
      ctx.send = render.bind(ctx)
      await next()
  }
}

const path = require('path')
const bodyParser = require('koa-bodyparser')
const nunjucks = require('koa-nunjucks-2')
const staticFiles = require('koa-static')

const miSend = require('./mi-send')
module.exports = (app) => {
  app.use(staticFiles(path.resolve(__dirname, "../public")))

  app.use(nunjucks({
    ext: 'html',
    path: path.join(__dirname, '../views'),
    nunjucksConfig: {
      trimBlocks: true
    }
  }));

  app.use(bodyParser())
  app.use(miSend())
}

const Koa = require('koa')
const app = new Koa()
const router = require('./router')
const middleware = require('./middleware')

middleware(app)
router(app)

app.listen(3000, () => {
  console.log('server is running at http://localhost:3000')
})

 ctx.send({
       status: 'success',
       data: '流量'
 })

npm i nodemon -save

"start": "node app.js"

"start": "nodemon app.js"

"start": "export NODE_ENV=dev && nodemon app.js",
"prd": "export NODE_ENV=product && nodemon app.js",

console.log('\n app.env: \n',app.env);
console.log('\n app.env: \n', process.env);

import Sequelize from 'sequelize';

const sequelize = new Sequelize('数据库名', '账户', '密码', {
    host: '连接主机',
    port: 5432, //端口
    dialect: 'postgres', //数据库,这里我们用postgre,你也可以选择mysql
    dialectOptions: {
        ssl: true   //适用于postgre非常关键,远程连接postgre需要通过ssl
    },
    pool: {
        max: 5,
        min: 0,
        idle: 10000
    }
});

sequelize.sync();

export default sequelize;

import Sequelize from 'sequelize';

export default function(sequelize) {
  const users = sequelize.define('users', {
    password: {
      allowNull: false,
      type: Sequelize.STRING,
      unique: true,
      validate: { isLowercase: true }
    },
    username: {
      type: Sequelize.STRING,
      unique: true
    }
  });
}

import users from './models/users.model';

users(sequelize);

import sequelize from '../db';
//注意下面这个属性:
const users = sequelize.models.users;