How would you parse a url in Ruby to get the main domain?

Question

I want to be able to parse any url with ruby to get the main part of the domain without the www (just the XXXX.com)

Answer 1

Just a short note: to overcome the second parsing of the url from Mischas second example, you could make a string comparison instead of URI.parse.

# Only parses once
def get_host_without_www(url)
  url = "http://#{url}" unless url.start_with?('http')
  uri = URI.parse(url)
  host = uri.host.downcase
  host.start_with?('www.') ? host[4..-1] : host
end

The downside of this approach is, that it is limiting the url to http(s) based urls, which is widely the standard. But if you will use it more general (f.e. for ftp links) you have to adjust accordingly.