Selector::prepareStringValue

protected function prepareStringValue(array $row, $name)
{
	if (empty($row[$name]) || !is_string($row[$name]))
	{
		return null;
	}
	$row[$name] = trim($row[$name]);
	if ($row[$name] === '')
	{
		return null;
	}
	return $row[$name];
}