How to use gsub to extract the id of a youtube video?

Question

I have to extract http://www.youtube.com/watch?v=aNdMiIAlK0g the video id from this url. Anyone know how do this using gsub and regex?

Answer 1

You can match the v parameter with this regexp:

url[/(?<=[?&]v=)[^&$]+/] # => aNdMiIAlK0g

It starts with a lookbehind for ? or & and matches everything up until the next & or the end of the string. It works even if there are other parameters, even those ending in "v".

However, a safer way to do it might be to use the URI class:

require 'uri'

query_string = URI.parse(url).query
parameters = Hash[URI.decode_www_form(query_string)]
parameters['v'] # => aNdMiIAlK0g

Answer 2

this is it:

ruby-1.9.2-p0 > "http://www.youtube.com/watch?v=aNdMiIAlK0g"[/v=([^&]+)/, 1]
 => "aNdMiIAlK0g"

(although you may want to use the URI library to get the query part and split them using & and use the value for v, because the above will get confused if the url is something like http://www.youtube.com/promo?for_tv=1 and it will take it as v=1)