Create an API Endpoint in WordPress

If you’re looking to setup a nice URI structure for an API endpoint within WordPress, there are a few approaches to accomplish this.

Approaches

1. Add a literal directory to your docroot and load WordPress outside of a typical index request with wp-load.php. This can cause some headaches and you have code residing outside of WordPress to maintain.

2. Create a page and assign an API endpoint page template. This is not too desirable as other editors/admins can easily touch this page.

3. Create an endpoint with a rewrite rule.

Example

I created an example API endpoint to serve up pug bombs from the ever awesome Pug Bomb API. You can download the fully functional API endpoint plugin here. Here’s the code:

<?php /* Plugin Name: Pug Bomb API Endpoint Description: Adds an API endpoint at /api/pugs/$n_pugs Version: 0.1 Author: Brian Fegter Author URL: http://coderrr.com */ class Pugs_API_Endpoint{ /** * @var string Pug Bomb Headquarters */ protected $api = 'http://pugme.herokuapp.com/bomb?count='; /** Hook WordPress * @return void */ public function __construct(){ add_filter('query_vars', array($this, 'add_query_vars'), 0); add_action('parse_request', array($this, 'sniff_requests'), 0); add_action('init', array($this, 'add_endpoint'), 0); } /** Add public query vars * @param array $vars List of current public query vars * @return array $vars */ public function add_query_vars($vars){ $vars[] = '__api'; $vars[] = 'pugs'; return $vars; } /** Add API Endpoint * This is where the magic happens - brush up on your regex skillz * @return void */ public function add_endpoint(){ add_rewrite_rule('^api/pugs/?([0-9]+)?/?','index.php?__api=1&pugs=$matches[1]','top'); } /** Sniff Requests * This is where we hijack all API requests * If $_GET['__api'] is set, we kill WP and serve up pug bomb awesomeness * @return die if API request */ public function sniff_requests(){ global $wp; if(isset($wp->query_vars['__api'])){ $this->handle_request(); exit; } } /** Handle Requests * This is where we send off for an intense pug bomb package * @return void */ protected function handle_request(){ global $wp; $pugs = $wp->query_vars['pugs']; if(!$pugs) $this->send_response('Please tell us how many pugs to send.'); $pugs = file_get_contents($this->api.$pugs); if($pugs) $this->send_response('200 OK', json_decode($pugs)); else $this->send_response('Something went wrong with the pug bomb factory'); } /** Response Handler * This sends a JSON response to the browser */ protected function send_response($msg, $pugs = ''){ $response['message'] = $msg; if($pugs) $response['pugs'] = $pugs; header('content-type: application/json; charset=utf-8'); echo json_encode($response)."\n"; exit; } } new Pugs_API_Endpoint();

Once you activate the plugin, you will need to visit the Permalinks page to flush the rewrite rules.

Overview

Here’s a brief overview of how this works:

– A rewrite rule is added for /api/pugs/{N_PUGS} and passes a hidden query var __api and number of pugs.

– An api request sniffer watches for the query variable __api and sends the request to be processed and subsequently kills the rest of the WordPress processes.

– The pug bomb request is validated and processed a JSON response is sent to the browser with an error or pug bomb goodness.

Feel free to ping me if you have any questions. Enjoy the script and hug a pug!

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