Node KOA框架入门

const koa = require(‘koa‘);
const Router = require(‘koa-router‘);

let server = new koa();
server.listen(8520,()=>{console.log(‘success‘);});

//普通路由
let router = new Router();
router.get(‘/a‘, async ctx=>{
    //ctx:上下文对象
    ctx.body=‘aaa‘;
    ctx.body+=‘bbb‘;
    console.log(ctx.body);
})
//把router怼给server才能生效
server.use(router.routes());

//1.嵌套路由:
/user
    /company
    /person
    /admin
/news
    /sport
    /woman
    /man
/car
...

const Router = require(‘koa-router‘);

let router = new Router();

router.get(‘/‘,async ctx=>{
    ctx.body=‘用户‘;
})
router.use(‘/company‘,require(‘./company‘))
router.use(‘/admin‘,require(‘./admin‘))

module.exports=router.routes();

const Router = require(‘koa-router‘);

let router = new Router();

router.get(‘/a‘,async ctx=>{
    ctx.body=‘管理员的a‘;
})

module.exports=router.routes();

const Router = require(‘koa-router‘);
let router = new Router();
router.get(‘/a‘,async ctx=>{
    ctx.body=‘企业的a‘;
});
module.exports=router.routes();

let router = new Router();
router.use(‘/user‘,require(‘./routers/user‘));
server.use(router.routes());

//2.参数:
http://localhost:8520/news/12
http://localhost:8520/news/123/889
http://localhost:8520/news/123/555/146

quretion1: 用?id=xxx传参和/:id的区别
urlencoded      http://aaa.com/user?a=12&b=5
params          http://aaa.com/user/12/5

    urlencoded        params
    顺序灵活          顺序是死的
    可以省略          不可省略的
    不利于SEO         利于SEO(因为地址是静态的)　

const Koa = require(‘koa‘);
const Router = require(‘koa-router‘);

let server = new Koa();
server.listen(8520);

let router = new Router();

router.get(‘/news/:id‘,async ctx=>{
    console.log(ctx.params);
    let {id} = ctx.params
    ctx.body=`新闻${id}`;
});

router.get(‘/news/:id/:id2‘,async ctx=>{
    console.log(ctx.params);
    let {id,id2} = ctx.params
    ctx.body=`新闻${id}_${id2}`;
});

router.get(‘/news/:id/:id2/:id3‘,async ctx=>{
    console.log(ctx.params);
    let {id,id2,id3} = ctx.params
    ctx.body=`新闻${id}_${id2}_${id3}`;
});

server.use(router.routes());

const Koa = require(‘koa‘);
const Router = require(‘koa-router‘);

let server = new Koa();
server.listen(8520,()=>{console.log(‘success‘);});

let router = new Router();

router.get(‘/news/‘,async ctx=>{
    console.log(ctx.query);
    let {id} = ctx.query;
});

server.use(router.routes());

熟悉ctx对象

server.context:相当于ctx的prototype
所以server.context适合放全局的东西

ctx.request
ctx.response

信息:
ctx.method      请求方法
ctx.url         请求地址
ctx.path        请求路径
ctx.query       get数据
ctx.ip          客户端ip
ctx.headers     请求头

比较方便的报错方法:

ctx.throw       //报错并且退出
eg:
if(!ctx.query.user || !ctx.query.pass){
    ctx.throw(400,‘user and password is required‘)
}else{
    ctx.body=‘成功‘;
}

ctx.assert()    //断言测试
ctx.assert(条件,code,msg)==if(!条件)ctx.throw
eg:
ctx.assert(ctx.query.user,400,‘username is required‘)