core-bundle/src/Resources/contao/models/FilesModel.php
public static function findById($intId, array $arrOptions=array())
	{
		if (Validator::isUuid($intId))
		{
			return static::findByUuid($intId, $arrOptions);
		}

		return static::findOneBy('id', $intId, $arrOptions);
	}
public static function findById($intId, array $arrOptions=array())
	{
		if (Validator::isUuid($intId))
		{
			return static::findByUuid($intId, $arrOptions);
		}

		return static::findOneBy('id', $intId, $arrOptions);
	}
Find a file by its ID or UUID

@param mixed $intId      The ID or UUID
@param array $arrOptions An optional options array

@return FilesModel|null The model or null if there is no file