Rails plugin that provides a validates_url_format_of method to ActiveRecord models. URLs are validated by regexp.
After installing the plugin, it's used like
class User < ActiveRecord::Base
validates_url_format_of :url,
:allow_nil => true,
:message => 'is completely unacceptable'
end
Takes the same arguments as validates_format_of except for the :with regexp.
The default :message is different depending on whether the attribute name contains the word "URL". So you will get "Homepage URL does not appear to be valid" but "Homepage does not appear to be a valid URL" without having to customize the :message.
Please note that the regexp used to validate URLs is not perfect, but hopefully good enough. See the test suite. Patches are very welcome.
Does not handle IPv6.
By design, the plugin does not allow e.g. "http://localhost" or "http://my.localurl", which are valid URLs but not suitable in most web apps. It also requires a "http://" or "https://" prefix, so just "example.com" is not valid. Fix that in the setter.