CarrierWave: create 1 uploader for multiple types of files

Question

I want to create 1 uploader for multiple types of files (images, pdf, video)

For each content_type will different actions

How I can define what content_type of file?

For example:

if image?
  version :thumb do
    process :proper_resize    
  end
elsif video?
  version :thumb do
    something
  end
end

Answer 1

I came across this, and it looks like an example of how to solve this problem: https://gist.github.com/995663.

The uploader first gets loaded when you call mount_uploader, at which point things like if image? or elsif video? won't work, because there is no file to upload defined yet. You'll need the methods to be called when the class is instantiated instead.

What the link I gave above does, is rewrite the process method, so that it takes a list of file extensions, and processes only if your file matches one of those extensions

# create a new "process_extensions" method.  It is like "process", except
# it takes an array of extensions as the first parameter, and registers
# a trampoline method which checks the extension before invocation
def self.process_extensions(*args)
  extensions = args.shift
  args.each do |arg|
    if arg.is_a?(Hash)
      arg.each do |method, args|
        processors.push([:process_trampoline, [extensions, method, args]])
      end
    else
      processors.push([:process_trampoline, [extensions, arg, []]])
    end
  end
end

# our trampoline method which only performs processing if the extension matches
def process_trampoline(extensions, method, args)
  extension = File.extname(original_filename).downcase
  extension = extension[1..-1] if extension[0,1] == '.'
  self.send(method, *args) if extensions.include?(extension)
end

You can then use this to call what used to be process

IMAGE_EXTENSIONS = %w(jpg jpeg gif png)
DOCUMENT_EXTENSIONS = %(exe pdf doc docm xls)
def extension_white_list
  IMAGE_EXTENSIONS + DOCUMENT_EXTENSIONS
end

process_extensions IMAGE_EXTENSIONS, :resize_to_fit => [1024, 768]

For versions, there's a page on the carrierwave wiki that allows you to conditionally process versions, if you're on >0.5.4. https://github.com/jnicklas/carrierwave/wiki/How-to%3A-Do-conditional-processing. You'll have to change the version code to look like this:

version :big, :if => :image? do
  process :resize_to_limit => [160, 100]
end

protected
def image?(new_file)
  new_file.content_type.include? 'image'
end