preview

# File railties/lib/rails/mailers_controller.rb, line 21
  def preview
    if params[:path] == @preview.preview_name
      @page_title = "Mailer Previews for #{@preview.preview_name}"
      render action: "mailer"
    else
      @email_action = File.basename(params[:path])

      if @preview.email_exists?(@email_action)
        @page_title = "Mailer Preview for #{@preview.preview_name}##{@email_action}"
        @email = @preview.call(@email_action, params)

        if params[:part]
          part_type = Mime::Type.lookup(params[:part])

          if part = find_part(part_type)
            response.content_type = part_type
            render plain: part.respond_to?(:decoded) ? part.decoded : part
          else
            raise AbstractController::ActionNotFound, "Email part '#{part_type}' not found in #{@preview.name}##{@email_action}"
          end
        else
          @part = find_preferred_part(request.format, Mime[:html], Mime[:text])
          render action: "email", layout: false, formats: [:html]
        end
      else
        raise AbstractController::ActionNotFound, "Email '#{@email_action}' not found in #{@preview.name}"
      end
    end
  end