/**
* Returns string usable by PHP's date functions, null if the format is not matched,
* or FALSE if this is not a date field.
*
* @param string $fieldValue
* @return false|null|string
*/
public function getDateTimeFormatString($fieldValue)
{
if (!is_string($fieldValue) || '' === $fieldValue) {
return null;
}
if (false === $this->_dateFormatSought) {
if ($this->isDateTimeField()) {
$this->_dateTimeFormatString = ValueUtility::getFieldDateTimeFormatString($fieldValue);
} else {
$this->_dateTimeFormatString = false;
}
$this->_dateFormatSought = true;
}
return $this->_dateTimeFormatString;
}
