default_url无法使用CarrierWave（Rails4）

Question

如果用户没有上传图片，我想显示默认图片。这是我的picture_uploader.rb，我将default.png上传到/ images / fallback。但我无法让它发挥作用。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

根据您的default_url，您的图片名称应为thumb_default.png：

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