Snippet to parse dynamic field and hold its values if the form submission returns back to the same page

fiDynamicFields.php

<?php

/**
 * fiDynamicFields snippet
 *
 * the snippet to manipulate this dynamic form, to parse the HTML code and
 * to hold the submitted values if the page goes back to the same page.
 *
 * @link http://www.virtudraft.com/blog/dynamic-fields-in-multiple-pages-for-formit.html
 * @author goldsky <[email protected]>
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3
 */
/**
 * &itemTpl=`a chunk name`
 * Chunk name as template to render each row
 */
$itemTpl = $modx->getOption('itemTpl', $scriptProperties);

/**
 * &wrapperTpl=`a chunk name`
 * (optional)
 * Chunk name to wrap rendered items and place the javascript code.
 * Leave this empty/unused if the javascript code is added directly in the template.
 */
$wrapperTpl = $modx->getOption('wrapperTpl', $scriptProperties);

if (empty($itemTpl)) {
    $modx->log(modX::LOG_LEVEL_ERROR, '[fiDynamicFields] is missing &itemTpl');
    return;
}

$phsPrefix = $modx->getOption('phsPrefix', $scriptProperties, 'dynfield.');
if (!isset($_POST)) {
    return;
}

$reverting = array();
foreach ($_POST as $k => $v) {
    if (!is_array($v)) {
        continue;
    }
    $i = 0;
    foreach ($v as $key => $val) {
        $reverting[$key][$phsPrefix.'idx']    = $i;
        $reverting[$key][$phsPrefix.$k] = $val;
        $i++;
    }
}

$items = array();
foreach ($reverting as $phs) {
    $items[] = $modx->getChunk($itemTpl, $phs);
}
if (empty($wrapperTpl)) {
    return @implode("\n", $items);
} else {
    $wrapper = array(
        $phsPrefix.'items' => @implode("\n", $items),
    );
    $output  = $modx->getChunk($wrapperTpl, $wrapper);

    return $output;
}