Example wordpress REST route

test.php

<?php
// http://my-site.com/wp-json/pandora/avatar
function my_func()
{
  register_rest_route( 'pandora', '/avatar', array(
          'methods'  => \WP_REST_Server::READABLE,
          'callback' => 'my_call',
      )
  );
}

function my_call()
{
  $class = new stdClass();
  $class->test = 'This is what is going to be out';
  return $class;
}

add_action( 'rest_api_init', 'my_func', 0 );