This is a simple Ruby gem that just enscapsulates directory naming scheme for carrierwave's file storage, enabling creation of directory structure that will be efficient and survive subdirectories limit.

If you have plenty of attachments you can encounter slowdowns or OS will reject creating next subdirectory at some point.

It is due to the fact that some filesystems have limit of subdirectories (for example: 64000 in ext4, until you enable the file system feature flag dir_nlink). Moreover, having a flat subdirectories structure can be suboptimal.

Create directory structure of the following syntax:

(ROOT_PATH)/(model class)/(mounted as)/(record's ID in hex split into groups of max 3 characters)/(file name)

For example:

/home/myrailsapp/public/system/User/Avatar/af7/233/1a3/12/whatever.mp3

Add to your Gemfile:

gem "carrierwave-hex-prefix-for-file-storage"

and then type:

bundle install

Then include it in your Uploader:

class SourceBodyUploader < CarrierWave::Uploader::Base
  include CarrierWave::Uploader::HexPrefixForFileStorage
  
  storage :file

  def store_dir
    store_dir_with_hex_prefix 
  end
end

Optionally, you can pass a parameter to store_dir_with_hex_prefix in order to change root path (by default it is RAILS_ROOT/public/system):

class SourceBodyUploader < CarrierWave::Uploader::Base
  include CarrierWave::Uploader::HexPrefixForFileStorage
  
  storage :file

  def store_dir
    store_dir_with_hex_prefix Rails.root.join("my_directory")
  end
end

0.0.1 - Initial release

MIT