[Express] Level 5: Route file

Using a Router Instance

Let's refactor app.js to use a Router object.

Create a new router object and assign it to the router variable.

var router = express.Router();

When we are done, our router will be mounted on the /cities path. With this in mind, change app.route('/cities') to use router and map requests to the root path.

app.route('/cities')
  .get(function (request, response) {
    if(request.query.search){
      response.json(citySearch(request.query.search));
    }else{
      response.json(cities);
    }
  })

//to

router.route('/')
  .get(function (request, response) {
    if(request.query.search){
      response.json(citySearch(request.query.search));
    }else{
      response.json(cities);
    }
  })

Likewise, let's move our '/cities/:name' route to our router. Remember to update the path.

app.route('/cities/:name')
  .get(function (request, response) {
    var cityInfo = cities[request.cityName];
    if(cityInfo){
      response.json(cityInfo);
    }else{
      response.status(404).json("City not found");
    }
  })

  .delete(function (request, response) {
    if(cities[request.cityName]){
      delete cities[request.cityName];
      response.sendStatus(200);
    }else{
      response.sendStatus(404);
    }
  });

//to

router.route('/:name')
  .get(function (request, response) {
    var cityInfo = cities[request.cityName];
    if(cityInfo){
      response.json(cityInfo);
    }else{
      response.status(404).json("City not found");
    }
  })

  .delete(function (request, response) {
    if(cities[request.cityName]){
      delete cities[request.cityName];
      response.sendStatus(200);
    }else{
      response.sendStatus(404);
    }
  });

Our router is now ready to be used by app. Mount our new router under the /cities path.

app.use('/cities', router);

var express = require('express');
var app = express();

var bodyParser = require('body-parser');
var parseUrlencoded = bodyParser.urlencoded({ extended: false });

// In memory store for the
// cities in our application
var cities = {
  'Lotopia': 'Rough and mountainous',
  'Caspiana': 'Sky-top island',
  'Indigo': 'Vibrant and thriving',
  'Paradise': 'Lush, green plantation',
  'Flotilla': 'Bustling urban oasis'
};

app.param('name', function (request, response, next) {
  request.cityName = parseCityName(request.params.name);
});

var router = express.Router();
app.use('/cities', router);
router.route('/')
  .get(function (request, response) {
    if(request.query.search){
      response.json(citySearch(request.query.search));
    }else{
      response.json(cities);
    }
  })

  .post(parseUrlencoded, function (request, response) {
    if(request.body.description.length > 4){
      var city = createCity(request.body.name, request.body.description);
      response.status(201).json(city);
    }else{
      response.status(400).json('Invalid City');
    }
  });

router.route('/:name')
  .get(function (request, response) {
    var cityInfo = cities[request.cityName];
    if(cityInfo){
      response.json(cityInfo);
    }else{
      response.status(404).json("City not found");
    }
  })

  .delete(function (request, response) {
    if(cities[request.cityName]){
      delete cities[request.cityName];
      response.sendStatus(200);
    }else{
      response.sendStatus(404);
    }
  });



// Searches for keyword in description
// and returns the city
function citySearch(keyword) {
  var regexp = RegExp(keyword, 'i');
  var result = cities.filter(function (city) {
    return city.match(regexp);
  });

  return result;
}

// Adds a new city to the
// in memory store
function createCity(name, description){
  cities[name] = description;
  return name;
}

// Uppercase the city name.
function parseCityName(name){
  var parsedName = name[0].toUpperCase() + name.slice(1).toLowerCase();
  return parsedName;
}

app.listen(3000);

All HTTP Verbs

What function would you call to match all HTTP verbs?

Answer:

app.all();

Using All

Let's use the app.all() method to handle the name parameter instead of app.param().

Add a call to all() for our router's '/:name' route. Pass a callback function that accepts request, response, and next.

router.route('/:name')
    .all(function(request, response, next){
  
  })

Now let's take our logic from the callback function passed to app.param()and move it to our all() callback.

router.route('/:name')
    .all(function(request, response, next){
    request.cityName = parseCityName(request.params.name);
  })

var express = require('express');
var app = express();

var bodyParser = require('body-parser');
var parseUrlencoded = bodyParser.urlencoded({ extended: false });

// In memory store for the cities in our application
var cities = {
  'Lotopia': 'Rough and mountainous',
  'Caspiana': 'Sky-top island',
  'Indigo': 'Vibrant and thriving',
  'Paradise': 'Lush, green plantation',
  'Flotilla': 'Bustling urban oasis'
};

// Searches for keyword in description and returns the city
function citySearch(keyword) {
  var regexp = RegExp(keyword, 'i');
  var result = cities.filter(function (city) {
    return city.match(regexp);
  });

  return result;
}

// Adds a new city to the in memory store
function createCity(name, description) {
  cities[name] = description;
  return name;
}

// Uppercase the city name.
function parseCityName(name) {
  var parsedName = name[0].toUpperCase() + name.slice(1).toLowerCase();
  return parsedName;
}

var router = express.Router();

router.route('/')
  .get(function (request, response) {
    if(request.query.search) {
      response.json(citySearch(request.query.search));
    } else {
      response.json(cities);
    }
  })

  .post(parseUrlencoded, function (request, response) {
    if(request.body.description.length > 4) {
      var city = createCity(request.body.name, request.body.description);
      response.status(201).json(city);
    } else {
      response.status(400).json('Invalid City');
    }
  });

router.route('/:name')
    .all(function(request, response, next){
    request.cityName = parseCityName(request.params.name);
  })
  .get(function (request, response) {
    var cityInfo = cities[request.cityName];
    if(cityInfo) {
      response.json(cityInfo);
    } else {
      response.status(404).json("City not found");
    }
  })

  .delete(function (request, response) {
    if(cities[request.cityName]) {
      delete cities[request.cityName];
      response.sendStatus(200);
    } else {
      response.sendStatus(404);
    }
  });

app.use('/cities', router);

app.listen(3000);

Creating a Router Module

Our single application file is growing too long. It's time we extract our routes to a separate Node module under the routes folder.

Move our router and its supporting code from app.js toroutes/cities.js.

routes/cities.js

var bodyParser = require('body-parser');
var parseUrlencoded = bodyParser.urlencoded({ extended: false });

// In memory store for the
// cities in our application
var cities = {
  'Lotopia': 'Rough and mountainous',
  'Caspiana': 'Sky-top island',
  'Indigo': 'Vibrant and thriving',
  'Paradise': 'Lush, green plantation',
  'Flotilla': 'Bustling urban oasis'
};

var router = express.Router();

router.route('/')
  .get(function (request, response) {
    if(request.query.search){
      response.json(citySearch(request.query.search));
    }else{
      response.json(cities);
    }
  })

  .post(parseUrlencoded, function (request, response) {
    if(request.body.description.length > 4){
      var city = createCity(request.body.name, request.body.description);
      response.status(201).json(city);
    }else{
      response.status(400).json('Invalid City');
    }
  });

router.route('/:name')
  .all(function (request, response, next) {
    request.cityName = parseCityName(request.params.name);
  })

  .get(function (request, response) {
    var cityInfo = cities[request.cityName];
    if(cityInfo){
      response.json(cityInfo);
    }else{
      response.status(404).json("City not found");
    }
  })

  .delete(function (request, response) {
    if(cities[request.cityName]){
      delete cities[request.cityName];
      response.sendStatus(200);
    }else{
      response.sendStatus(404);
    }
  });

// Searches for keyword in description
// and returns the city
function citySearch(keyword) {
  var regexp = RegExp(keyword, 'i');
  var result = cities.filter(function (city) {
    return city.match(regexp);
  });

  return result;
}

// Adds a new city to the
// in memory store
function createCity(name, description){
  cities[name] = description;
  return name;
}

// Uppercase the city name.
function parseCityName(name){
  var parsedName = name[0].toUpperCase() + name.slice(1).toLowerCase();
  return parsedName;
}

export our router object so other files can have access to it. Remember, Node - therefore Express - uses the CommonJS module specification.

module.exports = router;

Our cities routes module is now ready to be used from app.js. Require the new routes/cities module from app.js and assign it to a variable calledrouter;

app.js

var router = require('./routes/cities');