This code crumb will query a WordPress database using WP REST. It tackles all the basic steps to interact and get data from the WordPress database in three different ways; directly from the browser using a URL, calling from a PHP function or by a user-driven event from the front-end interface using Javascript which will then call a PHP function which in turn will query the database and return the result.

Register an Endpoint

function register_route() {
   register_rest_route('get-user/v1', '/first/(?P<first>.+)/last/(?P<last>.+)', [
      'methods' => 'GET',
      'callback' => 'get_user_callback',
      'permission_callback' => '__return_true',
add_action('rest_api_init', 'register_route');

Step 2. Create the Callback Function that Will Query the Database

  • Create the callback function for the endpoint
  • Get reference to the WordPress Database Access object (wpdb).
  • Get the parameters passed to the endpoint.
  • Prepare the database query using wpdb->prepare. Use ‘%s’ for string, ‘%d’ for integer and ‘%f’ for float values.
  • Query the database and get results. Use wpdb->get_results for SELECT statements and wpdb->query for DELETE/UPDATE.
  • Return the data in a WP_REST_Response object.

function get_user_callback(WP_REST_Request $request) {
   global $wpdb;
   $first_name = urldecode($request->get_param( 'first' ));
   $last_name = urldecode($request->get_param( 'last' ));
   $query = "SELECT * FROM 'users_table' WHERE 'first_name' = %s AND 'last_name' = %s";
   $prepared_query = $wpdb->prepare($query, $first_name, $last_name);
   $data = $wpdb->get_results($prepared_query);
   return new WP_REST_Response($data);

Call Call Directly From a Browser using a URL

  • Call directly from a browser by prefixing the Route with /wp-json/.

With parameters: (first name = ‘Gieon Felice’ and last name = ‘Aborot’) Felice/last/Aborot

Call the Endpoint From PHP

function call_from_php() {

   $response = wp_remote_get(
      " Felice/last/Aborot", [
         'sslverify' => false,
   if ( is_wp_error( $response ) ) {
      return new WP_Error( 'call_from_php unsuccessful', $response->get_error_message() );
   return wp_remote_retrieve_body($response);


Trigger the Call to the Endpoint From the Front-end Using Javascript

  • In PHP, declare the ajax_url object using wp_localize_script. This is needed to call the PHP function from JS using the AJAX request.
  • Add wordpress hooks to make a connection between the AJAX request action and the name of php function to call. ‘wp_ajax_nopriv’ fires ONLY if the user is not logged-in while ‘wp_ajax’ fires ONLY if the user is logged-in.
  • Create a PHP function which will be called from Javascript and in turn will call the Endpoint.
  • Finally in Javascript, create the function that will make an AJAX request to call the PHP function.

   [ 'ajax_url' => admin_url( 'admin-ajax.php' ) ]

add_action('wp_ajax_nopriv_call_from_js_to_php', 'call_from_php');
add_action('wp_ajax_call_from_js_to_php', 'call_from_php');

function call_from_php() {

   $first_name = $_GET['first_name'];
   $last_name = $_GET['last_name'];

   $response = wp_remote_get(
      "$first_name/last/$last_name", [
         'sslverify' => false,

   if ( is_wp_error( $response ) ) {
      return new WP_Error( 'call_from_php unsuccessful', $response->get_error_message() );

   wp_send_json(wp_remote_retrieve_body($response), 200);

function call_from_js() {
   jQuery.ajax(my_ajax_object.ajax_url, {
      type: 'GET',
      data: {
            action: 'call_from_js_to_php',
            first_name: 'Gieon Felice',
            last_name: 'Aborot',
   }).done(response => {
      const parsedResults = JSON.parse(response);
      // Do something with the result
   }).fail(error => {
      // Do something when an unsuccessful