Expressjs到Koajs-路由和模板？

Question

I am looking to migrate my Express app to Koa but I have no idea how to get the route and template working in Koa. It seems that there is documentation about this on their official site.

For instance this is how I would do it in Express:

var express = require('express');
var app = express();

// respond with "Hello World!" on the homepage
app.get('/', function (req, res) {
    res.send('Hello World!');
});

// accept POST request on the homepage
app.post('/', function (req, res) {
    res.send('Got a POST request');
});

// accept PUT request at /user
app.put('/user', function (req, res) {
    res.send('Got a PUT request at /user');
});

// accept DELETE request at /user
app.delete('/user', function (req, res) {
    res.send('Got a DELETE request at /user');
})

How is this done in Koa then? What I get from their doc:

const Koa = require('koa');
const app = new Koa();

app.use(async ctx => {
  ctx.body = 'Hello World';
});

app.listen(3000);

Also, when comes to the template rendering, in Express:

var express = require('express');
var router = express.Router();

router.get("/make", function(req, res) {

    return res.render("streams/make", {...});
});

So, how is this done in Koa?

Any ideas?

Answer 1

Koa doesn't provide this kind of thing out of the box - it's designed to be a little more low level than Express.

You'll need to either manually write your own middleware handling routing (via ctx.path and ctx.method ) and templating (grab the template engine from NPM and render to ctx.body ), or use one of the many pre-built solutions .

Answer 2

As mentioned already by Joe, Koa doesn't come with any middleware preinstalled.

For your needs, it seems like you would want to look into using koa-router and koa-views .

Usage:

app.js

const Koa = require('koa')
const views = require('koa-views')
const router = require('./routes')

const app = new Koa()

app.use(views(`${__dirname}/views`, { extension: 'pug' })) // You can replace 'pug' with whatever templating engine you're using.
app.use(router.routes())
app.use(router.allowedMethods())

app.listen(3000)

module.exports = app

routes.js

const Router = require('koa-router')

const router = new Router()

router.get('/', async ctx => {
  ctx.body = 'Hello World!'
})

// accept POST request on the homepage
router.post('/', async ctx => {
  ctx.body = 'Got a POST request'
})

// accept PUT request at /user
router.put('/user', async ctx => {
  ctx.body = 'Got a PUT request at /user'
})

// accept DELETE request at /user
router.delete('/user', async ctx => {
  ctx.body = 'Got a DELETE request at /user'
})

// Render a template
router.get("/make", async ctx => {
  await ctx.render("streams/make", { ... });
})

module.exports = router

With Koa, instead of getting the req and res as parameters, you just get a ctx . With this ctx object, you can access the request via ctx.request and the response with ctx.response . ctx.body is just an alias for ctx.response.body . Koa defines a lot of aliases for you, which you can read about here .