# koa-router
[](https://npmjs.org/package/koa-router) [](https://npmjs.org/package/koa-router) [](http://nodejs.org/download/) [](http://travis-ci.org/alexmingoia/koa-router) [](https://www.gratipay.com/alexmingoia/) [](https://gitter.im/alexmingoia/koa-router/)
> Router middleware for [koa](https://github.com/koajs/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](https://github.com/koajs/koa/tree/2.0.0-alpha.3) 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](https://www.npmjs.org/):
```sh
npm install koa-router
```
## API Reference
* [koa-router](#module_koa-router)
* [Router](#exp_module_koa-router--Router) ⏏
* [new Router([opts])](#new_module_koa-router--Router_new)
* _instance_
* [.get|put|post|patch|delete|del](#module_koa-router--Router+get|put|post|patch|delete|del) ⇒ <code>Router</code>
* [.routes](#module_koa-router--Router+routes) ⇒ <code>function</code>
* [.use([path], middleware)](#module_koa-router--Router+use) ⇒ <code>Router</code>
* [.prefix(prefix)](#module_koa-router--Router+prefix) ⇒ <code>Router</code>
* [.allowedMethods([options])](#module_koa-router--Router+allowedMethods) ⇒ <code>function</code>
* [.redirect(source, destination, code)](#module_koa-router--Router+redirect) ⇒ <code>Router</code>
* [.route(name)](#module_koa-router--Router+route) ⇒ <code>Layer</code> | <code>false</code>
* [.url(name, params)](#module_koa-router--Router+url) ⇒ <code>String</code> | <code>Error</code>
* [.param(param, middleware)](#module_koa-router--Router+param) ⇒ <code>Router</code>
* _static_
* [.url(path, params)](#module_koa-router--Router.url) ⇒ <code>String</code>
<a name="exp_module_koa-router--Router"></a>
### Router ⏏
**Kind**: Exported class
<a name="new_module_koa-router--Router_new"></a>
#### new Router([opts])
Create a new router.
| Param | Type | Description |
| --- | --- | --- |
| [opts] | <code>Object</code> | |
| [opts.prefix] | <code>String</code> | prefix router paths |
**Example**
Basic usage:
```javascript
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());
```
<a name="module_koa-router--Router+get|put|post|patch|delete|del"></a>
#### router.get|put|post|patch|delete|del ⇒ <code>Router</code>
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.
```javascript
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](https://github.com/pillarjs/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.
```javascript
router.get('user', '/users/:id', function (ctx, next) {
// ...
});
router.url('user', 3);
// => "/users/3"
```
#### Multiple middleware
Multiple middleware may be given:
```javascript
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:
```javascript
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:
```javascript
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`.
```javascript
router.get('/:category/:title', function (ctx, next) {
console.log(ctx.params);
// => { category: 'programming', title: 'how-to-node' }
});
```
The [path-to-regexp](https://github.com/pillarjs/path-to-regexp) module is
used to convert paths to regular expressions.
**Kind**: instance property of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type | Description |
| --- | --- | --- |
| path | <code>String</code> | |
| [middleware] | <code>function</code> | route middleware(s) |
| callback | <code>function</code> | route callback |
<a name="module_koa-router--Router+routes"></a>
#### router.routes ⇒ <code>function</code>
Returns router middleware which dispatches a route matching the request.
**Kind**: instance property of <code>[Router](#exp_module_koa-router--Router)</code>
<a name="module_koa-router--Router+use"></a>
#### router.use([path], middleware) ⇒ <code>Router</code>
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 <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type |
| --- | --- |
| [path] | <code>String</code> |
| middleware | <code>function</code> |
| [...] | <code>function</code> |
**Example**
```javascript
// 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());
```
<a name="module_koa-router--Router+prefix"></a>
#### router.prefix(prefix) ⇒ <code>Router</code>
Set the path prefix for a Router instance that was already initialized.
**Kind**: instance method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type |
| --- | --- |
| prefix | <code>String</code> |
**Example**
```javascript
router.prefix('/things/:thing_id')
```
<a name="module_koa-router--Router+allowedMethods"></a>
#### router.allowedMethods([options]) ⇒ <code>function</code>
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 <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type | Description |
| --- | --- | --- |
| [options] | <code>Object</code> | |
| [options.throw] | <code>Boolean</code> | throw error instead of setting status and header |
| [options.notImplemented] | <code>function</code> | throw the returned value in place of the default NotImplemented error |
| [options.methodNotAllowed] | <code>function</code> | throw the returned value in place of the default MethodNotAllowed error |
**Example**
```javascript
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](https://github.com/hapijs/boom)**
```javascript
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()
}));
```
<a name="module_koa-router--Router+redirect"></a>
#### router.redirect(source, destination, code) ⇒ <code>Router</code>
Redirect `source` to `destination` URL with optional 30x status `code`.
Both `source` and `destination` can be route names.
```javascript
router.redirect('/login', 'sign-in');
```
This is equivalent to:
```javascript
router.all('/login', function (ctx) {
ctx.redirect('/sign-in');
ctx.status = 301;
});
```
**Kind**: instance method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type | Description |
| --- | --- | --- |
| source | <code>String</code> | URL or route name. |
| destination | <code>String</code> | URL or route name. |
| code | <code>Number</code> | HTTP status code (default: 301). |
<a name="module_koa-router--Router+route"></a>
#### router.route(name) ⇒ <code>Layer</code> | <code>false</code>
Lookup route with given `name`.
**Kind**: instance method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type |
| --- | --- |
| name | <code>String</code> |
<a name="module_koa-router--Router+url"></a>
#### router.url(name, params) ⇒ <code>String</code> | <code>Error</code>
Generate URL for route. Takes a route name and map of named `params`.
**Kind**: instance method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type | Description |
| --- | --- | --- |
| name | <code>String</code> | route name |
| params | <code>Object</code> | url parameters |
**Example**
```javascript
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'));
})
```
<a name="module_koa-router--Router+param"></a>
#### router.param(param, middleware) ⇒ <code>Router</code>
Run middleware for named route parameters. Useful for auto-loading or
validation.
**Kind**: instance method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type |
| --- | --- |
| param | <code>String</code> |
| middleware | <code>function</code> |
**Example**
```javascript
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"}]
```
<a name="module_koa-router--Router.url"></a>
#### Router.url(path, params) ⇒ <code>String</code>
Generate URL from url pattern and given `params`.
**Kind**: static method of <code>[Router](#exp_module_koa-router--Router)</code>
| Param | Type | Description |
| --- | --- | --- |
| path | <code>String</code> | url pattern |
| params | <code>Object</code> | url parameters |
**Example**
```javascript
var url = Router.url('/users/:id', {id: 1});
// => "/users/1"
```
## Contributing
Please submit all issues and pull requests to the [alexmingoia/koa-router](http://github.com/alexmingoia/koa-router) repository!
## Tests
Run tests using `npm test`.
## Support
If you have any problem or suggestion please open an issue [here](https://github.com/alexmingoia/koa-router/issues).