Extending WP API - Code Sample 3

hm-api.php

namespace HM\REST_API;

class REST_API {

  public function __construct() {
    add_action('rest_api_init', array($this, 'register_routes'));
  }
  
  public function register_routes() {
    $api_namespace = 'hm/v1';
    
    // Register our first endpoint
    register_rest_route(
      $api_namespace,
      '/user',
      array(
        'methods'   => 'GET',
        'callback'  => array($this, 'get_user_callback')
      )
    );
  }
  
  public function get_user_callback( $request ) {
    $user_email = $request->get_param('email');
    $user = get_user_by( 'email', $user_email );
    if ( !$user ) {
      return array(
        'error' => 'User not found'
      );
    } else {
      return $user;
    }
  }

}

new REST_API();