Parsing youtube url

Question

I\'ve written a ruby youtube url parser. It\'s designed to take an input of a youtube url of one of the following structures (these are currently the youtube url structures tha

Answer 1

def parse_youtube url
   regex = /(?:.be\/|\/watch\?v=|\/(?=p\/))([\w\/\-]+)/
   url.match(regex)[1]
end

urls = %w[http://youtu.be/sGE4HMvDe-Q 
          http://www.youtube.com/watch?v=Lp7E973zozc&feature=relmfu
          http://www.youtube.com/p/A0C3C1D163BE880A?hl=en_US&fs=1]

urls.each {|url| puts parse_youtube url }
# sGE4HMvDe-Q
# Lp7E973zozc
# p/A0C3C1D163BE880A

Depending on how you use this, you might want a better validation that the URL is indeed from youtube.

UPDATE:

Coming back to this a few years later. I've always been annoyed by how sloppy the original answer was. Since the validity of the Youtube domain wasn't validated anyway, I've removed some of the slop.

NODE                     EXPLANATION
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  (?:                      group, but do not capture:
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    .                        any character except \n
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    be                       'be'
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    \/                       '/'
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   |                        OR
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    \/                       '/'
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    watch                    'watch'
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    \?                       '?'
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    v=                       'v='
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   |                        OR
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    \/                       '/'
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    (?=                      look ahead to see if there is:
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      p                        'p'
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      \/                       '/'
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    )                        end of look-ahead
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  )                        end of grouping
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  (                        group and capture to \1:
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    [\w\/\-]+                any character of: word characters (a-z,
                             A-Z, 0-9, _), '\/', '\-' (1 or more
                             times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
  )                        end of \1