Minimagick gem无法将多页PDF转换为多个png图像

我是RoR的新手，我正在尝试开发一个幻灯片共享应用程序，用户可以通过该应用程序上传和共享包含一副幻灯片（每页一张幻灯片）的多页PDF。 然后，观看者可以在“显示”页面上查看这些幻灯片。

在幕后我试图将多页pdf转换成几个.png文件（1 pdf页 – > 1.png文件），然后以轮播/滑块的方式显示它们。

这是我的上传者：

# encoding: utf-8 class DocUploader < CarrierWave::Uploader::Base # Include RMagick or MiniMagick support: # include CarrierWave::RMagick include CarrierWave::MiniMagick # Choose what kind of storage to use for this uploader: storage :file # storage :fog # Override the directory where uploaded files will be stored. # This is a sensible default for uploaders that are meant to be mounted: def store_dir # 'public/doc_uploads/' "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}" end process :filename process :generate_png def generate_png pdf = MiniMagick::Image.new(self.file.path) pdf.pages.each_with_index do |page, index| page.write("page#{index}.png") end end # Add a white list of extensions which are allowed to be uploaded. # For images you might use something like this: def extension_white_list %w(pdf) end # Override the filename of the uploaded files: # Avoid using model.id or version_name here, see uploader/store.rb for details. def filename 'doc.pdf' if original_filename end end 

当我尝试上传多页pdf文档时，它会抛出这个错误： 'identify /public/uploads/tmp/1443619784-406-3861/doc.pdf' failed with error:在pdf.pages.each_with_index do |page, index|

我已经尝试了不同的解决方案来转换文档，但到目前为止它们都没有对我有用。 为什么磨机.pdf文件的运行会失败minimagick的validation？ 有什么办法可以避免遇到这个问题吗？ 任何建议将不胜感激！