Add-a-custom-Express-route.md

title	lang	layout	toc	keywords	tags	sidebar	permalink	summary
Add a custom Express route	ja	page	false	LoopBack	getting_started	ja_lb3_sidebar	/doc/ja/lb3/Add-a-custom-Express-route.html	Because LoopBack is built on Express, you can add custom routes just as you do in Express.

{% include content/ja/gs-prereqs.html %}

In this part of the tutorial, you're going to add a new custom route.

{% include note.html content=" If you followed the previous steps in the tutorial, skip down to Introducing boot scripts.

If you're just jumping in, follow the steps below to catch up... " %}

Get the app (in the state following the last article) from GitHub and install all its dependencies:

$ git clone https://github.com/strongloop/loopback-getting-started.git
$ cd loopback-getting-started
$ git checkout step4
$ npm install

Introducing boot scripts

When a LoopBack application starts (or "bootstraps"), it runs the scripts in the /server/boot directory, known as boot scripts.  By default, LoopBack loads boot scripts in alphabetical order.  

The standard scaffolded LoopBack application created by the application generator contains the following standard boot scripts (in /server/boot) that perform basic initialization:

• authentication.js - Enables authentication for the application by calling app.enableAuth().
• root.js - Defines a root route to / that returns server status using loopback.status() middleware.  You already encountered this in the previous step, when you renamed this file so your app could serve static content.

For more information on boot scripts, see Defining boot scripts.

Add a new boot script

For example, add a new boot script named routes.js in /server/boot directory, with this code:

{% include code-caption.html content="/server/boot/routes.js" %}

module.exports = function(app) {
  // Install a "/ping" route that returns "pong"
  app.get('/ping', function(req, res) {
    res.send('pong');
  });
}

As an aside, you could have just as well used Express router middleware instead, like this:

{% include code-caption.html content="/server/boot/routes.js" %}

module.exports = function(app) {
  var router = app.loopback.Router();
  router.get('/ping', function(req, res) {
    res.send('pongaroo');
  });
  app.use(router);
}

In fact you can also add routes right in server.js using the Express API.  For example, add this call to app.use() just before the call to app.start():

{% include code-caption.html content="server/server.js" %}

...
app.use('/express-status', function(req, res, next) {
  res.json({ running: true });
});

// start the server if `$ node server.js`
if (require.main === module) {
  app.start();
}

The point is that a LoopBack application can easily do all the things that an Express application can.  If you're familiar with Express, this will make LoopBack easier to learn and use.

Run the boot script

Now, run the application again:

$ node .

Load http://0.0.0.0:3000/ping.  You'll see "pong" as the response. 

{% include next.html content="Check out Next steps for information on what to read next." %}