0

I have 

  file_ext = attach.document_file_name.capture(/\.[^.]*$/)

but i guess there is no method capture.

I'm trying to get the file extension from a string. I don't yet have the file.

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  • There's no need to start all of your questions with "Ruby on Rails" or "Regex" - that's what tags are for. Commented Jul 20, 2010 at 17:50

4 Answers 4

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10

There is also the built-in ruby function File.extname:

file_ext = File.extname(attach.document_file_name)

(with the difference that File.extname('hello.') returns '', whereas your regex would return '.')

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1 Comment

+1 Why mess with regular expressions when there is a function that does exactly what you want
3

How about:

file_ext = attach.document_file_name[/\.[^.]*$/]
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Note that it returns nil if no extension is found. If you prefer an empty string, append a to_s at the end of line.
2

You can do RegEx match in ruby like so:

file_ext = (/\.[^.]*$/.match(attach.document_file_name.to_s)).to_s

Fore more information please check http://ruby-doc.org/core/classes/Regexp.html

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2

If you want to use an regexp to do this, you can simply do:

irb(main):040:0> "foo.txt"[/\w*.(\w*)/,1]
=> "txt"
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