CarrierWave secure download url with CanCan for restrict permission

add following method to config/routes.rb

secure_download_map

default path is /secure_download but if you want to change path, use

secure_download_map :path => "your_path"

then change store_dir in your carrierwave uploader class to other path outside of public dir

Next, if you mount uploader in User model with this line

mount_uploader :file, FileUploader

and you want any user to be able to download this file then, add this rule to CanCan in ability.rb with format download_*.

can :download_file, User

Where file is mount name and User is a model that mount the file. You can add more specific permission, see more at https://github.com/ryanb/cancan/wiki/Defining-Abilities

Normally, you use user.file.url, when this gem was added, use user.file.secure_url instead. If you don't want user to be forced to download, use user.file.secure_url(true)