Automatically prepending url’s with http://

Recently we added functionality that allowed users to include links to images that they uploaded to one of our sites. In order to make the experience as easy as possible for users we allowed them to enter the url with or without the protocol (http:// or https://).

In order to make sure that any of our models that stored the information would always return a link with the protocol in it I wanted to create a simple mixin that would override the existing link method returned from the database and prepend http:// to it if it needed to.

Checking for the protocol and inserting it
This is actually quite a simple method. The following code was used to override the source_url method that was returning the link from the database.

def source_url
  link = super
  "#{link.match(/(http|https):\/\//i) ? '' : 'http://'}#{link}"

Since I was going to add this to a number of models it made sense to convert this to a mixin that could be used on any of the modules.

module Protocolize
  def self.included(klass)
    klass.class_eval do
      def self.protocolize(link_method)
        define_method link_method.to_sym do
          link = super()
          return nil if link.blank?
          "#{link.match(/(http|https):\/\//i) ? '' : 'http://'}#{link}"

This can then be called using the following in your model:

include Protocolize
protocolize :method_name

Notice that you have to explicitly call super() with params and not just super when you use it within define_method. If you don’t you will get the following error:

implicit argument passing of super from method defined by define_method() is not supported. Specify all arguments explicitly.

Just a tiny snippet that might be useful to people to ensure their links work correctly.


About Steve Smith
Software developer (often ruby, rails but I enjoy loads of languages), semantic tech. fanboy, skydiver, all round geek. Owner of dynamic:edge (hire us) the makers of

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