Renaming uploaded files with Carrierwave

Question

I'm using Carrierwave to upload files, and I have it working.

My issue is attempting to change the name of the uploaded file.

In the generated uploader.rb there is a method I think I should be using

def filename    "something.jpg" if original_filename    basename = "what"+orginal_filename if original_filename, works    basename = (0...8).map{65.+(rand(25)).chr}.join if original_filename  # will create a random name for each version, e.g. the orginal, the thumb, and the filename in the db, useless  end 

I can't seem to access items like 'extension' or 'content_type' in sanitized_file.rb, so this is a bit beyond my current skill level right now.

Any suggestions or exercises for doing this, i.e. generate filename for an uploaded file that works as well as the carrierwave default (do nothing, but does carry on to each version)? Seems like it should be simple enough but I've stumbled over this.

Answer 1

Well, another problem with your random filename generator is that it's possible to have collisions isn't it? You could possibly generate a filename that was already generated. One way to go about it would be to somehow generate a hash based on unique properties of the image, like file path. An example, from the carrierwave group:

def filename    if original_filename      @name ||= Digest::MD5.hexdigest(File.dirname(current_path))     "#{@name}.#{file.extension}"   end end 

This will create an MD5 hash based on the current path and then append the original file's extension to it.

Edit: The carrierwave wiki added an entry with a few methods on how to create random and unique filenames for all versioned files.

Answer 2

To have a real unique filename (not almost unique) I recommend to use the uuid gem.

in Gemfile add:

gem 'uuid' 

in file_uploader.rb:

def filename   if original_filename     if model && model.read_attribute(mounted_as).present?       model.read_attribute(mounted_as)     else       @name ||= "#{mounted_as}-#{uuid}.#{file.extension}"     end   end end  protected  def uuid   UUID.state_file = false   uuid = UUID.new   uuid.generate end