Node.js Rest Service Calls

In many instances, an application may need to make a call to a REST service to retrieve relevant information. The Node.js request package offers support for this sort of task.

Begin by creating a Node.js application using Handlebars as the template engine. You can either use your IDE or follow this tutorial to do this from the command line.

Once you have created a skeleton project, head over to OMDB to request an API key. You will get an email that will contain an API key. Then type npm install request to install the request package. Once you have the email, create a keys.js file in the routes folder.

keys.js

The keys.js file is used to hold API keys. Since API keys are like passwords, it’s generally a bad idea to push them to a public repository. By placing them in a file, you can import the keys into a project and then add them to .gitignore to keep them save. Here is what the keys.js file should look like.

exports.omdb_api = 'Your API Key';

index.js

The index.js is used for HTTP GET and POST requests to our application. You can view this tutorial to get an idea of how MVC works in Node.js with Express. We are going to mainly focus on the POST portion of this file.

var express = require('express');
var router = express.Router();
var key = require('./keys.js').omdb_api;
var request = require('request');

var movie = [];

/* GET home page. */
router.get('/', function (req, res) {
    res.render('index', { title: 'Rest Example', movie: movie });
});

router.post('/', function(req, res){
    var query = req.body.query;
    var url = 'http://www.omdbapi.com/?apikey=' + key + '&t=' + query + '&y=&plot=short&r=json';

    //Clear out movie
    movie = [];

    request(url, function(error, response, body){
        //Check for HTTP Status OK
        if (response.statusCode === 200){
            //Convert the body to a JSON object
            var json = JSON.parse(body);

            //Check if it has an error
            if(json.Error){
                movie = json.Error;
            } else {
                //Otherwise, add our movie information to movie
                movie.push({
                    title: json.Title,
                    year: json.Year,
                    imdb: json.Ratings[0].Value,
                    tomatoes: json.Ratings[1].Value,
                    country: json.Country,
                    plot: json.Plot,
                    actors: json.Actors
                });
            }
        } else {
            //We had something other than HTTP OK
            //Push an error to movie and just pass the body
            movie.push({Error: body});
        }
        //Render the index page
        res.render('index', {title: 'Rest Example', movie: movie[0]});
    });
});

module.exports = router;

We begin on line 3, where we import our keys.js file and grab it’s omdb_api variable. This variable holds our API key and will be used to create our URL for our web request. On line 6, we create a movie variable and initialize it to an empty array.

Our POST handler is located on line 13. One line 14, we grab the name of the movie the user wishes to inspect from the req.body.query variable. On line 15, we assemble our url by adding our API key and movie name to the url string.

Line 20 uses the request package to make a call to the OMBD API. It takes two parameters, a url and a call back function. The callback function can have 3 parameters: error, response, and body. We are interested in response and body in this case. Our first job is to check the HTTP status code from response.statusCode. If everything is OK, the response will be 200 (for HTTP OK). Assuming all went well, we can convert the body variable into a JSON object so that we can access the properties of the response.

If the user happens to enter a move that doesn’t exist, the json will have an Error property. We will just assign this to the movie variable is that’s the case. Otherwise, we can create a new object containing title, year, imdb, tomatoes, country, plot, and actors (lines 31-38) and push it to movies. Finally we can return the reponse body back to the view and render the index page (line 47).

layout.hbs

We need to add our Jquery and Bootstrap libraries to our layout.hbs file so that they are available to our pages.
layout

index.hbs

This page renders the results our request.
index.js
The main take away is that we use the {{#if [value]}} markup so that the template engine can decide if it wants to render the error or movie information.

Conclusion

When everything is complete you will get a site that looks like the one shown in the screenshots below.


You can view the full source at my GitHub page here.

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