[Plugin: WP-Blocks] Getting a random block by regex

This shouldn’t be WP version specific.

function get_wp_block_random($block_slug_regex) {
    global $wpdb;
    $block_slug_regex = trim($block_slug_regex);
    $data = (array)$wpdb->get_results("SELECT id FROM {$wpdb->prefix}wpb_content WHERE name REGEXP '{$block_slug_regex}' AND active = TRUE");
    if (isset($data) && is_array($data) && count($data) > 0)
    {
      $arrayIndex = array();
      foreach ($data as $row)
      {
        $arrayIndex[] = $row->id;
      }
      $randomIndex = mt_rand(0, count($arrayIndex) - 1);

      return get_wp_block_by_id($arrayIndex[$randomIndex]);
    }
  }

This will allow you to get a single random block based upon a regex. For example:
<?php get_wp_block_random('^testimonial_'); ?>
Will return a block which has a name starting with testimonial_

http://wordpress.org/extend/plugins/wp-blocks/