Create a JSON Endpoint in WordPress

If you’re a WordPress developer, sooner or later you’re going to need to create a JSON endpoint. Fortunately, WordPress makes it relatively easy to do so. In this blog post, we’ll show you how to create a JSON endpoint in WordPress.

The first thing you need to do is create a plugin. To do that, simply create a new folder in your WordPress installation’s wp-content/plugins directory. For this example, we’ll call the folder custom_rest. Inside that folder, create a new file called custom_rest.php. The contents of that file should be as follows: 

The contents of that file should be as follows: 

add_action('rest_api_init', function () {
  register_rest_route( 'custom-rest/v1', 'posts', [
            'methods'  => 'GET',
            'callback' => 'custom_rest_posts_by_types',
            'permission_callback' => function() {
		          return true;
		      }
  ]);
register_rest_route( 'custom-rest/v1', 'post/id/(?P<id>\d+)', [
            'methods'  => 'GET',
            'callback' => 'custom_rest_posts_by_id',
            'args' => [
		      'id' => [
		        'validate_callback' => function($param, $request, $key) {
		          return is_numeric( $param );
		        }
		      ],
		    ],
  ]);

});

function custom_rest_posts_by_types($request){
	$types = ['type_a', 'type_b', 'type_c'];

	global $wpdb;
	$result = [];

	foreach ($types as $type) {
		//get post by type
		$posts_by_type =  $wpdb->get_results("SELECT DISTINCT pm.post_id FROM {$wpdb->prefix}postmeta as pm WHERE pm.meta_key LIKE 'component_type' AND lower(pm.meta_value) LIKE '%".strtolower($type)."%'");
		$post_ids = [];
		foreach ($posts_by_type as $key => $p) {
			$result[$p->post_id] = [
				'id' => $p->post_id,
			];
		}

		
	}
	return new WP_REST_Response($result, 200);

}

function custom_rest_posts_by_id($request){
	$id = $request['id'];
	$post = get_post($id);
	return new WP_REST_Response([$post], 200);
}

Then any app can access this endpoint at http://example.com/wp-json/custom-rest/v2/posts and http://example.com/wp-json/custom-rest/v2/post/id/[id].