How to build a RESTful API?

Question

The issue is this: I have a web application that runs on a PHP server. I\'d like to build a REST api for it.
I did some research and I figured out that REST api uses HTT

Answer 1

As simon marc said, the process is much the same as it is for you or I browsing a website. If you are comfortable with using the Zend framework, there are some easy to follow tutorials to that make life quite easy to set things up. The hardest part of building a restful api is the design of the it, and making it truly restful, think CRUD in database terms.

It could be that you really want an xmlrpc interface or something else similar. What do you want this interface to allow you to do?

--EDIT

Here is where I got started with restful api and Zend Framework. Zend Framework Example

In short don't use Zend rest server, it's obsolete.

Answer 2

(1) How do I ... build those URI's? Do I need to write a PHP code at that URI?

There is no standard for how an API URI scheme should be set up, but it's common to have slash-separated values. For this you can use...

$apiArgArray = explode("/", substr(@$_SERVER['PATH_INFO'], 1));

...to get an array of slash-separated values in the URI after the file name.

Example: Assuming you have an API file api.php in your application somewhere and you do a request for api.php/members/3, then $apiArgArray will be an array containing ['members', '3']. You can then use those values to query your database or do other processing.

(2) How do I build the JSON objects to return as a response?

You can take any PHP object and turn it into JSON with json_encode. You'll also want to set the appropriate header.

header('Content-Type: application/json');
$myObject = (object) array( 'property' => 'value' ); // example
echo json_encode($myObject); // outputs JSON text

All this is good for an API that returns JSON, but the next question you should ask is:

(3) How do I make my API RESTful?

For that we'll use $_SERVER['REQUEST_METHOD'] to get the method being used, and then do different things based on that. So the final result is something like...

header('Content-Type: application/json');
$apiArgArray = explode("/", substr(@$_SERVER['PATH_INFO'], 1));
$returnObject = (object) array();
/* Based on the method, use the arguments to figure out
   whether you're working with an individual or a collection, 
   then do your processing, and ultimately set $returnObject */
switch ($_SERVER['REQUEST_METHOD']) {
  case 'GET':
    // List entire collection or retrieve individual member
    break;
  case 'PUT':       
    // Replace entire collection or member
    break;  
  case 'POST':      
    // Create new member
    break;
  case 'DELETE':    
    // Delete collection or member
    break;
}
echo json_encode($returnObject);

Sources: https://stackoverflow.com/a/897311/1766230 and http://en.wikipedia.org/wiki/Representational_state_transfer#Applied_to_web_services

Answer 3

Another framework which has not been mentioned so far is Laravel. It's great for building PHP apps in general but thanks to the great router it's really comfortable and simple to build rich APIs. It might not be that slim as Slim or Sliex but it gives you a solid structure.

See Aaron Kuzemchak - Simple API Development With Laravel on YouTube and

Laravel 4: A Start at a RESTful API on NetTuts+

Answer 4

Here is a very simply example in simple php.

There are 2 files client.php & api.php. I put both files on the same url : http://localhost:8888/, so you will have to change the link to your own url. (the file can be on two different servers).

This is just an example, it's very quick and dirty, plus it has been a long time since I've done php. But this is the idea of an api.

client.php

<?php

/*** this is the client ***/


if (isset($_GET["action"]) && isset($_GET["id"]) && $_GET["action"] == "get_user") // if the get parameter action is get_user and if the id is set, call the api to get the user information
{
  $user_info = file_get_contents('http://localhost:8888/api.php?action=get_user&id=' . $_GET["id"]);
  $user_info = json_decode($user_info, true);

  // THAT IS VERY QUICK AND DIRTY !!!!!
  ?>
    <table>
      <tr>
        <td>Name: </td><td> <?php echo $user_info["last_name"] ?></td>
      </tr>
      <tr>
        <td>First Name: </td><td> <?php echo $user_info["first_name"] ?></td>
      </tr>
      <tr>
        <td>Age: </td><td> <?php echo $user_info["age"] ?></td>
      </tr>
    </table>
    <a href="http://localhost:8888/client.php?action=get_userlist" alt="user list">Return to the user list</a>
  <?php
}
else // else take the user list
{
  $user_list = file_get_contents('http://localhost:8888/api.php?action=get_user_list');
  $user_list = json_decode($user_list, true);
  // THAT IS VERY QUICK AND DIRTY !!!!!
  ?>
    <ul>
    <?php foreach ($user_list as $user): ?>
      <li>
        <a href=<?php echo "http://localhost:8888/client.php?action=get_user&id=" . $user["id"]  ?> alt=<?php echo "user_" . $user_["id"] ?>><?php echo $user["name"] ?></a>
    </li>
    <?php endforeach; ?>
    </ul>
  <?php
}

?>

api.php

<?php

// This is the API to possibility show the user list, and show a specific user by action.

function get_user_by_id($id)
{
  $user_info = array();

  // make a call in db.
  switch ($id){
    case 1:
      $user_info = array("first_name" => "Marc", "last_name" => "Simon", "age" => 21); // let's say first_name, last_name, age
      break;
    case 2:
      $user_info = array("first_name" => "Frederic", "last_name" => "Zannetie", "age" => 24);
      break;
    case 3:
      $user_info = array("first_name" => "Laure", "last_name" => "Carbonnel", "age" => 45);
      break;
  }

  return $user_info;
}

function get_user_list()
{
  $user_list = array(array("id" => 1, "name" => "Simon"), array("id" => 2, "name" => "Zannetie"), array("id" => 3, "name" => "Carbonnel")); // call in db, here I make a list of 3 users.

  return $user_list;
}

$possible_url = array("get_user_list", "get_user");

$value = "An error has occurred";

if (isset($_GET["action"]) && in_array($_GET["action"], $possible_url))
{
  switch ($_GET["action"])
    {
      case "get_user_list":
        $value = get_user_list();
        break;
      case "get_user":
        if (isset($_GET["id"]))
          $value = get_user_by_id($_GET["id"]);
        else
          $value = "Missing argument";
        break;
    }
}

exit(json_encode($value));

?>

I didn't make any call to the database for this example, but normally that is what you should do. You should also replace the "file_get_contents" function by "curl".

Answer 5

I know that this question is accepted and has a bit of age but this might be helpful for some people who still find it relevant. Although the outcome is not a full RESTful API the API Builder mini lib for PHP allows you to easily transform MySQL databases into web accessible JSON APIs.

Answer 6

In 2013, you should use something like Silex or Slim

Silex example:

require_once __DIR__.'/../vendor/autoload.php'; 

$app = new Silex\Application(); 

$app->get('/hello/{name}', function($name) use($app) { 
    return 'Hello '.$app->escape($name); 
}); 

$app->run(); 

Slim example:

$app = new \Slim\Slim();
$app->get('/hello/:name', function ($name) {
    echo "Hello, $name";
});
$app->run();