Routers

const createRouter = require('@arangodb/foxx/router');

Routers let you define routes that extend ArangoDB’s HTTP API with custom endpoints.

Routers need to be mounted using the use method of a service context to expose their HTTP routes at a service’s mount path.

You can pass routers between services mounted in the same database as dependencies. You can even nest routers within each other.

Creating a router

createRouter(): Router

This returns a new, clean router object that has not yet been mounted in the service and can be exported like any other object.

Request handlers

router.get([path], [...middleware], handler, [name]): Endpoint

router.post([path], [...middleware], handler, [name]): Endpoint

router.put([path], [...middleware], handler, [name]): Endpoint

router.patch([path], [...middleware], handler, [name]): Endpoint

router.delete([path], [...middleware], handler, [name]): Endpoint

router.all([path], [...middleware], handler, [name]): Endpoint

These methods let you specify routes on the router. The all method defines a route that will match any supported HTTP verb, the other methods define routes that only match the HTTP verb with the same name.

Arguments

• path: string (Default: "/")

  The path of the request handler relative to the base path the Router is mounted at. If omitted, the request handler will handle requests to the base path of the Router. For information on defining dynamic routes see the section on path parameters in the chapter on router endpoints.

• middleware: Function (optional)

  Zero or more middleware functions that take the following arguments:

  • req: Request

    An incoming server request object.

  • res: Response

    An outgoing server response object.

  • next: Function

    A callback that passes control over to the next middleware function and returns when that function has completed.

    If a truthy argument is passed, that argument will be thrown as an error.

    If there is no next middleware function, the handler will be invoked instead (see below).

• handler: Function

  A function that takes the following arguments:

  • req: Request

    An incoming server request object.

  • res: Response

    An outgoing server response.

• name: string (optional)

  A name that can be used to generate URLs for the endpoint. For more information see the reverse method of the request object.

Returns an Endpoint for the route.

Examples

Simple index route:

router.get(function (req, res) {
  res.set('content-type', 'text/plain');
  res.write('Hello World!');
});

Restricting access to authenticated ArangoDB users:

router.get('/secrets', function (req, res, next) {
  if (req.arangoUser) {
    next();
  } else {
    res.throw(404, 'Secrets? What secrets?');
  }
}, function (req, res) {
  res.download('allOurSecrets.zip');
});

Multiple middleware functions:

function counting (req, res, next) {
  if (!req.counter) req.counter = 0;
  req.counter++;
  next();
  req.counter--;
}
router.get(counting, counting, counting, function (req, res) {
  res.json({counter: req.counter}); // {"counter": 3}
});

Mounting child routers and middleware

router.use([path], middleware, [name]): Endpoint

The use method lets you mount a child router or middleware at a given path.

Arguments

• path: string (optional)

  The path of the middleware relative to the base path the Router is mounted at. If omitted, the middleware will handle requests to the base path of the Router. For information on defining dynamic routes see the section on path parameters in the chapter on router endpoints.

• middleware: Router | Middleware

  An unmounted router object or a middleware.

• name: string (optional)

  A name that can be used to generate URLs for endpoints of this router. For more information see the reverse method of the request object. Has no effect if handler is a Middleware.

Returns an Endpoint for the middleware or child router.

Examples

const child = createRouter();

router.use("/a", child);

router.use("/b", child)
.queryParam("number", joi.number().required(), "Required number parameter.");

child.get(function (req, res) {
  // The query parameter "number" is required if the request was made via "/b"
  // but optional if the request was made via "/a", we can't rely on it.
  res.json({number: req.queryParams.number});
});

const child = createRouter()
.queryParam("number", joi.number().required(), "Required number parameter.");

router.use("/a", child);

router.use("/b", child);

child.get(function (req, res) {
  // The query parameter "number" is always required, regardless if the
  // request was made via "/a" or "/b".
  res.json({number: req.queryParams.number});
});

Additional metadata

In addition to the router-specific methods, all methods available on endpoints are also available on router objects and can be used to define shared defaults.

Examples

router.header(
  'x-common-header',
  joi.string().required(),
  'Common header shared by all routes on this router.'
);

router.get('/', function (req, res) {
  // This route requires the header to be set but we don't need to explicitly
  // specify that.
  const value = req.header('x-common-header');
  // ...
});