Undefined Method 'path' For StringIO in Ruby

Question

I'm using the following snippet in a Rails app:

require 'open-uri'
url = "http://..."
uri = URI.parse(self.url)
file = open(uri)
puts "path: #{file.path}"

Which works on some files from the web, then crashes on others with:

undefined method `path' for #< StringIO:0x00000102a47240 >

Any way to fix this strange, intermittent problem?

Answer 1

I'm definitely late to the party but...

The root of this problem is that if you use open(url) on a file smaller than 10kb it will convert it into a string IO object auto-magically instead of using a Tempfile. The StringIO object as everyone has pointed out does not have the path method defined on it.

The default (10kb) is set by the StringMax constant...

http://yard.ruby-doc.org/stdlib-2.1.0/OpenURI/Buffer.html

if defined?(OpenURI) && OpenURI::Buffer.const_defined?(StringMax)
  OpenURI::Buffer.send('remove_const', StringMax)
  OpenURI::Buffer.send('const_set', StringMax, 0)
end

Boom problem, solved!

p.s. make sure to use #send otherwise you can't access the #remove_const and #cont_set methods. p.p.s. I wouldn't advise setting it to zero if you do a lot of small IO as the tempfiles created will probably be worse than just changing your code to properly use StringIO. It all depends on yer use case.

Answer 2

Don't use Open::URI like that.

Simply do:

file = open(url)

Then you can read the file because you have an IO-type object:

body = file.read

or

body = open(url).read

If you need the path, parse the URL with URI and get the path that way.