User::convertTo

static function convertTo(FieldType $fieldType, $value, $toTypeClass)
{
	/** @var Base $toTypeClass */
	$type = $toTypeClass::getType();
	switch ($type)
	{
		case FieldType::DOUBLE:
		case FieldType::INT:
			$value = (string)$value;
			if (mb_strpos($value, 'user_') === 0)
				$value = mb_substr($value, mb_strlen('user_'));
			$value = (int)$value;
			break;
		case FieldType::STRING:
		case FieldType::TEXT:
		case FieldType::USER:
			$value = (string)$value;
			break;
		default:
			$value = null;
	}

	return $value;
}