Question

Something I’m not getting about the version process…

I have a zip file with a file inside, and I want to upload the file as a “version” of the zip:

Uploader:

  version :specificFile do
    process :extract_file
  end

  def extract_file
    file = nil
    Zip::ZipFile.open(current_path) do |zip_file|
      file = zip_file.select{|f| f.name.match(/specificFile/)}.first
      zip_file.extract(file, "tmp/" + file.name.gsub("/", "-")){ true }
    end    
    File.open("tmp/" + file.name.gsub("/", "-"))
  end

Usage:

=link_to "Specific File", instance.uploader.specificFile.url

Only this just nets me two copies of the zip. Clearly, there’s something I’m missing about how version / process works, and I haven’t been able to find documentation that actually explains the magic.

So how do I do this, and what am I missing?

Answer 1

This provided the “why”, although it took a bit to understand:
How do you create a new file in a CarrierWave process?

To rephrase, when you go to create a version, carrierwave makes a copy of the file and then passes the process the file path. When the process exits, carrierwave will upload the contents of that path – not the file the process returns, which is what I thought was going on.

Working code:

  version :specificFile do
    process :extract_file
    def full_filename (for_file = model.logo.file)
      "SpecificFile.ext"
    end
  end

  def extract_plist
    file = nil
    Zip::ZipFile.open(current_path) do |zip_file|
      file = zip_file.select{|f| f.name.match(/specificFile/)}.first
      zip_file.extract(file, "tmp/" + file.name.gsub("/", "-")){ true }
    end    
    File.delete(current_path)
    FileUtils.cp("tmp/" + file.name.gsub("/", "-"), current_path)
  end

So, to make what I want to happen, happen, I:

• Tell carrierwave to use a particular filename. I’m using a hardcoded value but you should be able to use whatever you want.

• Overwrite the contents of current_path with the contents you want under the version name. In my case, I can’t just overwrite the zip while I’m “in it” (I think), so I make a copy of the file I care about and overwrite the zip via File and FileUtils.

PS – It would be nice to avoid the duplication of the zip, but it doesn’t look like you can tell carrierwave to skip the duplication.