ruby-on-rails - CarrierWave:为多种类型的文件创建 1 个 uploader

Question

我想为多种类型的文件(图片、pdf、视频)创建 1 个 uploader

对于每个 content_type 会有不同的 Action

如何定义文件的内容类型？

例如:

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

Answer 1

我遇到过这个，它看起来像一个如何解决这个问题的例子:https://gist.github.com/995663 .

uploader 首先在您调用 mount_uploader 时加载，此时 if image? 或 elsif video? 将不起作用，因为还没有定义要上传的文件。您需要在实例化类时调用这些方法。

我在上面给出的链接所做的是重写 process 方法，以便它获取文件扩展名列表，并且仅当您的文件与其中一个扩展名匹配时才处理

# 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

然后你可以用它来调用以前的进程

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]

对于版本，carrierwave wiki 上有一个页面允许您有条件地处理版本，如果您使用的是 >0.5.4。 https://github.com/jnicklas/carrierwave/wiki/How-to%3A-Do-conditional-processing .您必须将版本代码更改为如下所示:

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

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