[Express] Level 3: Reading from the URL

City Search

We want to create an endpoint that we can use to filter cities. Follow the tasks below to to create this new route.

Create a new route for GET request to '/cities'. The second argument should be a callback function which takes request and response.

app.get('/cities', function(request , response){

});

From inside of our route, create an if statement that checks whether a value is set to the query string parameter search.

app.get('/cities', function(request , response){
  if(request.query.search){

  }
});

Inside of the if block, call the citySearch() function, passing in the user submitted parameter for search. Then return the result of the function as a JSON response.

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

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

var cities = ['Caspiana', 'Indigo', 'Paradise'];

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

function citySearch (keyword) {
  var regexp = RegExp(keyword, 'i');
  var result = cities.filter(function (city) {
    return city.match(regexp);
  });

  return result;
}

app.listen(3000);

Dynamic Route Variables

Consider the following Dynamic Route:

app.get('/cities/:name', function (request, response) {
  // ...
})

When requests come in for this route, how can we access the city name submitted by the user?

Answer:

requst.params.name

City Information

Now lets look up some information about the city.

Inside of our dynamic route, grab the name submitted by the user, lookup the city information on the cities object and assign it to the cityInfovariable.

var cities = {
  'Lotopia': 'Rough and mountainous',
  'Caspiana': 'Sky-top island',
  'Indigo': 'Vibrant and thriving',
  'Paradise': 'Lush, green plantation',
  'Flotilla': 'Bustling urban oasis'
};

app.get('/cities/:name', function (request, response) {
  var cityInfo,
      name;
  name = request.params.name;
  cityInfo = cities[name];
});

Check to see if cityInfo exists and if so, respond with the cityInfo in JSON format.

app.get('/cities/:name', function (request, response) {
  var cityInfo,
      name;
  name = request.params.name;
  cityInfo = cities[name];

  if(cityInfo){
      response.json(cityInfo);
  }
});

If cityInfo does not exist, respond with a 404 HTTP status code and a JSON message that says "City not found".

app.get('/cities/:name', function (request, response) {
  var cityInfo,
      name;
  name = request.params.name;
  cityInfo = cities[name];

  if(cityInfo){
      response.json(cityInfo);
  }else{
      response.status(404).json("City not found");
  }
});

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

var cities = {
  'Lotopia': 'Rough and mountainous',
  'Caspiana': 'Sky-top island',
  'Indigo': 'Vibrant and thriving',
  'Paradise': 'Lush, green plantation',
  'Flotilla': 'Bustling urban oasis'
};

app.get('/cities/:name', function (request, response) {
  var cityInfo,
      name;
  name = request.params.name;
  cityInfo = cities[name];

  if(cityInfo){
      response.json(cityInfo);
  }else{
      response.status(404).json("City not found");
  }
});

app.listen(3000);