How to check if a URL is valid

Question

How can I check if a string is a valid URL?

For example:

http://hello.it => yes
http:||bra.ziz, => no

If this is a valid URL

Answer 1

This is a fairly old entry, but I thought I'd go ahead and contribute:

String.class_eval do
    def is_valid_url?
        uri = URI.parse self
        uri.kind_of? URI::HTTP
    rescue URI::InvalidURIError
        false
    end
end

Now you can do something like:

if "http://www.omg.wtf".is_valid_url?
    p "huzzah!"
end

Answer 2

Use the URI module distributed with Ruby:

require 'uri'

if url =~ URI::regexp
    # Correct URL
end

Like Alexander Günther said in the comments, it checks if a string contains a URL.

To check if the string is a URL, use:

url =~ /\A#{URI::regexp}\z/

If you only want to check for web URLs (http or https), use this:

url =~ /\A#{URI::regexp(['http', 'https'])}\z/

Answer 3

You could also use a regex, maybe something like http://www.geekzilla.co.uk/View2D3B0109-C1B2-4B4E-BFFD-E8088CBC85FD.htm assuming this regex is correct (I haven't fully checked it) the following will show the validity of the url.

url_regex = Regexp.new("((https?|ftp|file):((//)|(\\\\))+[\w\d:\#@%/;$()~_?\+-=\\\\.&]*)")

urls = [
    "http://hello.it",
    "http:||bra.ziz"
]

urls.each { |url|
    if url =~ url_regex then
        puts "%s is valid" % url
    else
        puts "%s not valid" % url
    end
}

The above example outputs:

http://hello.it is valid
http:||bra.ziz not valid