title: Rails+carrierwave: default thumb for msword content type
body: <p>I`m use Rails 3.2.11+Carrierwave.
  help please, how to set the default thumb for a specific content type, such as .doc or .docx?
  Default thumb placed in /public/assets - thumb_for_doc.jpg</p>
  
  <p>my uploader:</p>
  
  <pre>
  
  
  
  
        # Include RMagick or MiniMagick support:
        include CarrierWave::RMagick
        #include CarrierWave::MiniMagick
        include CarrierWave::MimeTypes
  
        # Include the Sprockets helpers for Rails 3.1+ asset pipeline compatibility:
         include Sprockets::Helpers::RailsHelper
         include Sprockets::Helpers::IsolatedHelper
  
        # Choose what kind of storage to use for this uploader:
        storage :file
        # storage :fog
  
  
        def store_dir
          "uploads/order_#{model.order.id}" unless model.order.nil?
        end
  
        process :set_content_type
  
        version :pdf, :if => :pdf? do
          process :cover
          process :resize_to_fit => [100, 100]
          process :convert => :jpg
  
          def full_filename (for_file = model.source.file)
            super.chomp(File.extname(super)) + '.jpg'
          end
        end
  
        version :msword, :if => :msword? do
          #????
        end
  
        version :thumb, :if => :image? do
          process :resize_to_limit => [100, 100]
        end
  
        def filename
          if model.document_specification_id
            document_specification = Lists::DocumentSpecification.find_by_id(model.document_specification_id)
            margins = Lists::PrintMargin.find_by_id(document_specification.print_margin_id).margin
            paper_type = Lists::PaperType.find_by_id(Lists::PaperSpecification.find_by_id(document_specification.paper_specification_id).paper_type_id).paper_type
            paper_size = Lists::PaperSize.find_by_id(Lists::PaperSpecification.find_by_id(document_specification.paper_specification_id).paper_size_id).size
            "#{secure_token}_PP_#{paper_size.parameterize}_#{paper_type.parameterize}_#{model.quantity}_#{margins.parameterize}.#{file.extension}" if original_filename.present?
          else
            "#{secure_token}_PP_not_set_spesification.#{file.extension}" if original_filename.present?
          end
        end
  
        def cover
          manipulate! do |frame, index|
            frame if index.zero? # take only the first page of the file
          end
        end
  
        protected
          def secure_token
            var = :"@#{mounted_as}_secure_token"
            model.instance_variable_get(var) or model.instance_variable_set(var, SecureRandom.hex(4))
          end
  
          def image?(file)
            file.content_type.start_with? 'image'
          end
  
          def pdf?(file)
            file.content_type.start_with? 'application/pdf' 
          end
  
          def msword?(file)
            file.content_type.start_with? 'application/msword' 
          end
      end
  
  </pre>
  
  <p>thanks!</p>