Koa Trie Router

About

Trie routing for Koa based on routington.

Routes are orthogonal and strict, so the order of definition doesn't matter.
Unlike regexp routing, there's no wildcard routing and you can't next to the next matching route.

See routington for more details.

Versions

• Koa@1 is compatible with 1.x.x versions of Trie-router
• Koa@2 is compatible with 2.x.x versions

Features

• Express-style routing using router.get, router.put, router.post, etc
• Named URL parameters
• Responds to OPTIONS requests with allowed methods
• Multiple route middleware
• Multiple routers
• Nestable routers
• 405 Method Not Allowed support
• 501 Not Implemented support

Notes

The router handles /foo and /foo/ as the different urls (see why one, two). If you need the same behavior for these urls just add koa-no-trailing-slash on the top of your middleware queue.

Usage

const Koa = require('koa')
const Router = require('koa-trie-router')

let app = new Koa()
let router = new Router()

router
  .use(function(ctx, next) {
    console.log('* requests')
    return next()
  })
  .get(function(ctx, next) {
    console.log('GET requests')
    return next()
  })
  .put('/foo', function (ctx) {
    ctx.body = 'PUT /foo requests'
  })
  .post('/bar', function (ctx) {
    ctx.body = 'POST /bar requests'
  })

app.use(router.middleware())
app.listen(3000)

API

router.use(middleware...)

Handles all requests

router.use(function(ctx) {
  ctx.body = 'test' // All requests
})

router[method](middleware...)

Handles requests only by one HTTP method

router.get(function(ctx) {
  ctx.body = 'GET' // GET requests
})

router[method](paths, middleware...)

Handles requests only by one HTTP method and one route

Where

• paths is {String|Array<String>}
• middleware is {Function|Array<Function>|AsyncFunction|Array<AsyncFunction>}

Signature

router
  .get('/one', middleware)
  .post(['/two','/three'], middleware)
  .put(['/four'], [middleware, middleware])
  .del('/five', middleware, middleware, middleware)

router.middleware()

Like Express, all routes belong to a single middleware.

You can use koa-mount for mounting of multiple routers:

const Koa = require('koa')
const mount = require('koa-mount')
const Router = require('koa-trie-router')

let app = new Koa()
let router1 = new Router()
let router2 = new Router()

router1.get('/foo', middleware)
router2.get('/bar', middleware)

app.use(mount('/foo', router1.middleware()))
app.use(mount('/bar', router2.middleware()))

router.isImplementedMethod(method)

Checks if the server implements a particular method and returns true or false. This is not middleware, so you would have to use it in your own middleware.

app.use(function(ctx, next) {
  if (!router.isImplementedMethod(ctx.method)) {
    ctx.status = 501
    return
  }
  return next()
})

ctx.request.params

ctx.request.params will be defined with any matched parameters.

router.get('/user/:name', async function (ctx, next) {
  let name = ctx.request.params.name // or ctx.params.name
  let user = await User.get(name)
  return next()
})

Error handling

The middleware throws an error with code MALFORMEDURL when it encounters a malformed path. An application can try/catch this upstream, identify the error by its code, and handle it however the developer chooses in the context of the application- for example, re-throw as a 404.

Path Definitions

For path definitions, see routington.