gistfile1.php

<?php 
    /**
     * Handle various type conversions that should be supported natively by Doctrine (like DateTime)
     *
     * @param  mixed  $value
     * @param  string $typeOfField
     * @return DateTime
     */
    protected function handleTypeConversions($value, $typeOfField)
    {
        switch($typeOfField) {
            case 'datetime':
            case 'time':
            case 'date':
                if ($value === '') {
                    return null;
                }

                if (is_int($value)) {
                    $dateTime = new DateTime();
                    $dateTime->setTimestamp($value);
                    $value = $dateTime;
                } elseif (is_string($value)) {
                    $value = new DateTime($value);
                }

                break;
            default:
        }