Question

I want to validate a URL in Rails using URI.Parse, by saying that the URL is valid as long as URI.parse does not raise URI::InvalidURIError. Is that a good idea? What URLs would pass this validation test?

Answer 1

Yes, it’s a good idea if you plan to use those URLs in your app.

URI will prove the string is parseable into these parts: scheme, userinfo, host, port,
registry, path, opaque, query, fragment.

URI handles these schemes:

• FTP, HTTP, HTTPS, LDAP, LDAPS, or MailTo
• or URI::Generic

http://www.ruby-doc.org/stdlib-1.9.3/libdoc/uri/rdoc/URI/Parser.html#method-i-parse

If you have other schemes, you can handle them yourself after the parse.

URI.parse works by calling URI.split, which uses two regular expressions:

• URI::ABS_URI for absolute URIs
• URI::REL_URI for relative URIs

You can look at these to see how they match. You can alter them too if you like.