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Using HTTP API's

Objectives

  1. Students will be able to express what an HTTP API is.
  2. Students will be able to use the request node module to make requests to an API.
  3. Students will be able to render json data from an API.

What is a HTTP API?

From Wikipedia: A server-side web API is a programmatic interface to a defined request-response message system, typically expressed in JSON or XML, which is exposed via the web—most commonly by means of an HTTP-based web server. Mashups are web applications which combine the use of multiple such web APIs.[1] Webhooks are server-side web APIs that take as input a URI that is designed to be used like a remote named pipe or a type of callback such that the server acts as a client to dereference the provided URI and trigger an event on another server which handles this event thus providing a type of peer-to-peer IPC.

While "web API" in this context is sometimes considered a synonym for web service, Web 2.0 web applications have moved away from SOAP-based web services towards more cohesive collections of RESTful web resources.[2] These RESTful web APIs are accessible via standard HTTP methods by a variety of HTTP clients including browsers and mobile devices.

...Wtf In short, an HTTP API, is a black box that we make requests to, and get responses from. Typically HTTP API's respond with JSON or XML. Nearly Every modern website uses an API, very often a website will consume its own API.

To turn Reddit into a JSON API, we simply add .json to the end of a reddit url like so http://www.reddit.com/new.json

Intro the Request module

To get started clone this repo HERE IS THE REPO.

$ npm install --save request

Then go look at the documentation for request by clicking here

It seems like the general structure of making requests with request is something like this:

// We require the module
var request = require('request');

// We use the request module to make a request to
// google.com. We pass in a callback that takes in three
// parameters, error, response, and body.
request('http://www.google.com', function (error, response, body) {
    if (!error && response.statusCode == 200) {
      console.log(body) // Show the HTML for the Google homepage. 
    }
});

Exercise 1: Use the request module to make a request to your favorite website. Hint: Note that you need to be in a node repl to do tihs (thats right an intentional typo!).

Here's an example:

request('http://www.reddit.com/new.json', function(err, response, body) {
    if (!err && response.statusCode == 200) {
      console.log("THIS IS THE RESPONSE", response);
      console.log("\n\n\n\n\n\n\n\n\n\nTHIS IS THE BODY", body);
    }
});

And now for the API that we'll be using in the lab today

OMDB is basically an IMDB clone that we can query. Unlike IMDB, OMDB will send back JSON. It makes it easy to use, I promise.

The two routes, we're going to need

Number 1: http://www.omdbapi.com?s=SEARCH+TERM+PLUS+DELIMITED. This important part from the link above is the ?s=SEARCH+TERM+PLUS+DELIMITED. An example of a query we're going to make.http://www.omdbapi.com?s=i+robot.

This makes a GET request where we're searching for a particular movie title.

Number 2: http://www.omdbapi.com?i=IMDBID. This important part from the link above is the ?i=IMDBID. An example of a query we're going to make.http://www.omdbapi.com?i=tt1083849.

This makes a GET request where we're searching for a particular movie with that IMDB ID.

Exercise 2: Lets use the request library to make requests to each of these URLs.

Note: Try doing something with the body of the request that you get back. Do you notice anything about it. Hint JSON.parse.

Now lets take a look at our app

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

app.set('view engine', 'ejs');

// We have our root route that renders our index view
app.get('/', function(req,res) {
  res.render('index');
});

// We have our search route that renders our search view
app.get('/search', function(req,res) {
  res.render('search', {movies: []});
});

// We have our movie route that renders our movie view
app.get('/movie', function(req,res) {
  res.render('movie', {movie: {Title: "I'm a movie", Plot: "I'm a plot"}});
});

app.listen(3000);

Our index page only has a form that has METHOD GET and action /search.

  <form method="GET" action="/search">
    <input type="text" name="q" placeholder="Search">
    <button>Click Me... I dare you.</button>
  </form>

This form is going to show up on the search page as well.

Our search page looks like this

  <h1> Movies: </h1>
  <% movies.forEach(function(movie) { %>
    <div>
      <div>
        <h3>Title:</h3>
        <a href="/movie?id=<%= movie.imdbID %>">
          <%= movie.Title %>
        </a>
     </div>
     <div>
       <h3>Plot:</h3>
       <p>
        <%= movie.Plot %>
       </p>
     </div>
    </div>
  <% }); %>

Sice we use the movies variable in our view, any route that renders this view must then pass along a {movies: SOME_ARRAY_GOES_HERE_} to the render function.

Group Exercise: I'll be doing it along with you. Inside of our app.get('/search', ...) method, we're going to make a request to the OMDB API and then render the search page with the parsed results of the request.

Exercise 3: Use request to make a request to the OMDB API to grab a particular movie by it's IMDB ID.