default_url 不适用于 CarrierWave (Rails4)

Question

如果用户不上传图片，我想显示默认图片。这是我的 picture_uploader.rb，我将 default.png 上传到 /images/fallback。但我无法让它工作。任何提示，我接下来可以尝试什么？

class PictureUploader < CarrierWave::Uploader::Base

  include CarrierWave::MiniMagick
  version :thumb do
    process :resize_to_fill => [150, 150]
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  def default_url
    "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  end
end

Answer 1

根据你的default_url，你的图片名称应该是thumb_default.png：

[2] pry(main)> version_name = 'thumb'
=> "thumb"
[3] pry(main)> [version_name, "default.png"].compact.join('_')
=> "thumb_default.png"