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koa-router

koa-router

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Router middleware for koa

  • Express-style routing using app.get, app.put, app.post, etc.
  • Named URL parameters.
  • Named routes with URL generation.
  • Responds to OPTIONS requests with allowed methods.
  • Support for 405 Method Not Allowed and 501 Not Implemented.
  • Multiple route middleware.
  • Multiple routers.
  • Nestable routers.
  • ES7 async/await support.

Migrating to 7 / Koa 2

  • The API has changed to match the new promise-based middleware signature of koa 2. See the koa 2.x readme for more information.
  • Middleware is now always run in the order declared by .use() (or .get(), etc.), which matches Express 4 API.

Installation

Install using npm:

npm install koa-router

API Reference

Router ⏏

Kind: Exported class

new Router([opts])

Create a new router.

Param Type Description
[opts] Object
[opts.prefix] String prefix router paths

Example
Basic usage:

var Koa = require('koa');
var Router = require('koa-router');
 
var app = new Koa();
var router = new Router();
 
router.get('/', function (ctx, next) {
  // ctx.router available 
});
 
app
  .use(router.routes())
  .use(router.allowedMethods());

router.get|put|post|patch|delete|del ⇒ Router

Create router.verb() methods, where verb is one of the HTTP verbs such as router.get() or router.post().

Match URL patterns to callback functions or controller actions using router.verb(), where verb is one of the HTTP verbs such as router.get() or router.post().

Additionaly, router.all() can be used to match against all methods.

router
  .get('/', function (ctx, next) {
    ctx.body = 'Hello World!';
  })
  .post('/users', function (ctx, next) {
    // ... 
  })
  .put('/users/:id', function (ctx, next) {
    // ... 
  })
  .del('/users/:id', function (ctx, next) {
    // ... 
  })
  .all('/users/:id', function (ctx, next) {
    // ... 
  });

When a route is matched, its path is available at ctx._matchedRoute and if named, the name is available at ctx._matchedRouteName

Route paths will be translated to regular expressions using path-to-regexp.

Query strings will not be considered when matching requests.

Named routes

Routes can optionally have names. This allows generation of URLs and easy renaming of URLs during development.

router.get('user', '/users/:id', function (ctx, next) {
 // ... 
});
 
router.url('user', 3);
// => "/users/3" 

Multiple middleware

Multiple middleware may be given:

router.get(
  '/users/:id',
  function (ctx, next) {
    return User.findOne(ctx.params.id).then(function(user) {
      ctx.user = user;
      next();
    });
  },
  function (ctx) {
    console.log(ctx.user);
    // => { id: 17, name: "Alex" } 
  }
);

Nested routers

Nesting routers is supported:

var forums = new Router();
var posts = new Router();
 
posts.get('/', function (ctx, next) {...});
posts.get('/:pid', function (ctx, next) {...});
forums.use('/forums/:fid/posts', posts.routes(), posts.allowedMethods());
 
// responds to "/forums/123/posts" and "/forums/123/posts/123" 
app.use(forums.routes());

Router prefixes

Route paths can be prefixed at the router level:

var router = new Router({
  prefix: '/users'
});
 
router.get('/', ...); // responds to "/users" 
router.get('/:id', ...); // responds to "/users/:id" 

URL parameters

Named route parameters are captured and added to ctx.params.

router.get('/:category/:title', function (ctx, next) {
  console.log(ctx.params);
  // => { category: 'programming', title: 'how-to-node' } 
});

The path-to-regexp module is used to convert paths to regular expressions.

Kind: instance property of Router

Param Type Description
path String
[middleware] function route middleware(s)
callback function route callback

router.routes ⇒ function

Returns router middleware which dispatches a route matching the request.

Kind: instance property of Router

router.use([path], middleware) ⇒ Router

Use given middleware.

Middleware run in the order they are defined by .use(). They are invoked sequentially, requests start at the first middleware and work their way "down" the middleware stack.

Kind: instance method of Router

Param Type
[path] String
middleware function
[...] function

Example

// session middleware will run before authorize 
router
  .use(session())
  .use(authorize());
 
// use middleware only with given path 
router.use('/users', userAuth());
 
// or with an array of paths 
router.use(['/users', '/admin'], userAuth());
 
app.use(router.routes());

router.prefix(prefix) ⇒ Router

Set the path prefix for a Router instance that was already initialized.

Kind: instance method of Router

Param Type
prefix String

Example

router.prefix('/things/:thing_id')

router.allowedMethods([options]) ⇒ function

Returns separate middleware for responding to OPTIONS requests with an Allow header containing the allowed methods, as well as responding with 405 Method Not Allowed and 501 Not Implemented as appropriate.

Kind: instance method of Router

Param Type Description
[options] Object
[options.throw] Boolean throw error instead of setting status and header
[options.notImplemented] function throw the returned value in place of the default NotImplemented error
[options.methodNotAllowed] function throw the returned value in place of the default MethodNotAllowed error

Example

var Koa = require('koa');
var Router = require('koa-router');
 
var app = new Koa();
var router = new Router();
 
app.use(router.routes());
app.use(router.allowedMethods());

Example with Boom

var Koa = require('koa');
var Router = require('koa-router');
var Boom = require('boom');
 
var app = new Koa();
var router = new Router();
 
app.use(router.routes());
app.use(router.allowedMethods({
  throw: true,
  notImplemented: () => new Boom.notImplemented(),
  methodNotAllowed: () => new Boom.methodNotAllowed()
}));

router.redirect(source, destination, code) ⇒ Router

Redirect source to destination URL with optional 30x status code.

Both source and destination can be route names.

router.redirect('/login', 'sign-in');

This is equivalent to:

router.all('/login', function (ctx) {
  ctx.redirect('/sign-in');
  ctx.status = 301;
});

Kind: instance method of Router

Param Type Description
source String URL or route name.
destination String URL or route name.
code Number HTTP status code (default: 301).

router.route(name) ⇒ Layer | false

Lookup route with given name.

Kind: instance method of Router

Param Type
name String

router.url(name, params) ⇒ String | Error

Generate URL for route. Takes a route name and map of named params.

Kind: instance method of Router

Param Type Description
name String route name
params Object url parameters

Example

router.get('user', '/users/:id', function (ctx, next) {
  // ... 
});
 
router.url('user', 3);
// => "/users/3" 
 
router.url('user', { id: 3 });
// => "/users/3" 
 
router.use(function (ctx, next) {
  // redirect to named route 
  ctx.redirect(ctx.router.url('sign-in'));
})

router.param(param, middleware) ⇒ Router

Run middleware for named route parameters. Useful for auto-loading or validation.

Kind: instance method of Router

Param Type
param String
middleware function

Example

router
  .param('user', function (id, ctx, next) {
    ctx.user = users[id];
    if (!ctx.user) return ctx.status = 404;
    return next();
  })
  .get('/users/:user', function (ctx) {
    ctx.body = ctx.user;
  })
  .get('/users/:user/friends', function (ctx) {
    return ctx.user.getFriends().then(function(friends) {
      ctx.body = friends;
    });
  })
  // /users/3 => {"id": 3, "name": "Alex"} 
  // /users/3/friends => [{"id": 4, "name": "TJ"}] 

Router.url(path, params) ⇒ String

Generate URL from url pattern and given params.

Kind: static method of Router

Param Type Description
path String url pattern
params Object url parameters

Example

var url = Router.url('/users/:id', {id: 1});
// => "/users/1" 

Contributing

Please submit all issues and pull requests to the alexmingoia/koa-router repository!

Tests

Run tests using npm test.

Support

If you have any problem or suggestion please open an issue here.