Joomla - K2 extrafield formating helper

k2helper.php

<?php 

class K2Helper
{
    /**
     * Convert K2 extra fields to an object
     *
     * Selectable extra fields ever return values inside an array
     * same if only one value is selected
     *
     * @param string|array $itemExtraFields
     *
     * @return null|stdClass
     */
    public static function getK2ExtraFields($itemExtraFields)
    {
        $itemExtraFieldsObject = new stdClass();
        if (is_string($itemExtraFields))
        {
            $itemExtraFields = json_decode($itemExtraFields);
        }

        if (count($itemExtraFields) == 0)
        {
            return null;
        }

        if (!isset($itemExtraFields[0]->alias))
        {
            $db = \JFactory::getDbo();
            $query =
                $db->getQuery(true)
                    ->select('id,value')
                    ->from('#__k2_extra_fields');

            $db->setQuery($query);
            $extraFields = $db->loadAssocList('id');
        }

        foreach ($itemExtraFields as $itemExtraField)
        {
            $extraFieldValues = json_decode($extraFields[$itemExtraField->id]['value']);

            if (!isset($itemExtraField->alias))
            {
                $itemExtraField->alias = json_decode($extraFields[$itemExtraField->id]['value'])[0]->alias;
            }

            // ignore unknown extra fields
            if (empty($itemExtraField->alias))
            {
                continue;
            }

            // simple extra-field (without selectable values)
            if (empty($extraFieldValues[0]->name))
            {
                $itemExtraFieldsObject->{$itemExtraField->alias} = $itemExtraField->value;
                continue;
            }

            // ONLY for extra-fields with selectable values

            if (!is_array($itemExtraField->value))
            {
                $itemExtraField->value = [$itemExtraField->value];
            }

            $values = [];
            foreach ($itemExtraField->value as $refValue)
            {
                foreach ($extraFieldValues as $extraFieldValue)
                {
                    if ($extraFieldValue->value == $refValue)
                    {
                        $values[] = $extraFieldValue->name;
                        break;
                    }
                }
            }

            $itemExtraFieldsObject->{$itemExtraField->alias} = $values;
        }

        return $itemExtraFieldsObject;
    }
}