rails saving recognized link from text to database with rinku - ruby-on-rails

Question

I have a rails app with chat. In the chat for the messages I use rinku gem to recognize links which works well. On the top of this I would like to save the links as message.link without the rest of the text around it from the message.body.
So for example in the code below the user sent the message.body "hi there www.stackoverflow.com" and I would like to save only the "www.stackoverflow.com" as message.link. How can I do that?
view
<p><%= find_links(message.body) %></p>
controller
def find_links(message_body)
Rinku.auto_link(message_body, mode=:all, 'target="_blank"', skip_tags=nil).html_safe
end
it will appear in the DOM as:
<p>hey there http://stackoverflow.com/</p>
and will appear in the db as message.body:
"hey there http://stackoverflow.com/"
UPDATE:
messages controller
require "uri"
def create
.....
if message.save
link = URI.extract(message.body)
update_attribute(message.link = link)
end

Answer 1

You need regular expression to identify URLs from text. Try following regular expression:
/(https?:\/\/(?:www\.|(?!www))[^\s\.]+\.[^\s]{2,}|www\.[^\s]+\.[^\s]{2,})/
Working demo: http://rubular.com/r/bHQdFHZYFH
2.1.2 :001 > str = "hey hi hello www.google.com https://stackoverflow.com http://tech-brains.blogspot.in"
2.1.2 :002 > regexp = /(https?:\/\/(?:www\.|(?!www))[^\s\.]+\.[^\s]{2,}|www\.[^\s]+\.[^\s]{2,})/
2.1.2 :003 > str.scan(regexp)
=> [["www.google.com"], ["https://stackoverflow.com"], ["http://tech-brains.blogspot.in"]]

Answer 2

You can use Ruby code:
2.0.0-p247 :001 > require "uri"
=> true
2.0.0-p247 :002 > URI.extract("hey there http://stackoverflow.com/")
=> ["http://stackoverflow.com/"]
Hope it helps!