如何在Rails 3.2中获得相对路径？

Question

我有一个文件列表，我尝试获取相对路径

file = "/Users/yves/github/local/workshop/public/uploads/craftwork/image/1/a1d0.jpg"
Rails.public_path => "/Users/yves/github/local/workshop/public"

＃我想得到=＆gt; “上传/工艺/图像/ 1 / a1d0.jpg”

file.relative_path_from(Rails.public_path) # is wrong 
# raising :  undefined method `relative_path_from' for #<String  ( file is a String..)

# so I tried to use Pathname class
Pathname.new(file).relative_path_from(Rails.public_path)

# but the I get another error
# undefined method `cleanpath' for String

Rails 3.2中是否弃用了relative_path_from？如果是的话，现在有什么好处？

Answer 1

由于这些属性现在返回字符串，我们可以将它们转换回路径名：

public_path = Pathname.new( Rails.public_path )
file_path = Pathname.new( file )

然后使用相对路径函数，最后将其转换回字符串

relative_path = file_path.relative_path_from( public_path ).to_s 

一起变成

Pathname.new( file ).relative_path_from( Pathname.new( Rails.public_path ) ).to_s 

Answer 2

您可以“欺骗”并使用sub ...

删除public_path

$ cat foo.rb 
file = "/Users/yves/github/local/workshop/public/uploads/craftwork/image/1/a1d0.jpg"
public_path = "/Users/yves/github/local/workshop/public"
puts file.sub(/^#{public_path}\//, '')

$ ruby foo.rb 
uploads/craftwork/image/1/a1d0.jpg

Answer 3

这就是我用过的：

"#{Rails.root}/public/spreadsheets/file_name.xlsx"