Remove subdomain from string in ruby

Question

I\'m looping over a series of URLs and want to clean them up. I have the following code:

# Parse url to remove http, path and check format
o_url = URI.parse(         


        

Answer 1

This is a tricky issue. Some top-level domains do not accept registrations at the second level.

Compare example.com and example.co.uk. If you would simply strip everything except the last two domains, you would end up with example.com, and co.uk, which can never be the intention.

Firefox solves this by filtering by effective top-level domain, and they maintain a list of all these domains. More information at publicsuffix.org.

You can use this list filter out everything except the domain right next to the effective TLD. I don't know of any Ruby library that does this, but it would be a great idea to release one!

Update: there are C, Perl and PHP libraries that do this. Given the C version, you could create a Ruby extension. Alternatively, you could port the code to Ruby.