Create a custom domain URL shortener with Rails

A few weeks ago I made a post about creating custom domain short URL services with bit.ly. I'm going to walk you through a simple Rails application that allows you to create a custom domain URL shortener for free!

Creating the Rails App

I'm going to assume that you know a little bit of Rails. First let's begin by creating our base Rails app and a few models. I will be calling my application leav.in (just because it's what I used in the previous post.

rails new leav.in

Let's create a very simple Link model:

rails c scaffold Link in_url:string out_url:text http_status:integer

Here's the breakdown of each field:

• in_url - the URL that we will search by
• out_url - the outgoing URL that we will redirect to
• http_status - the status we will attach to the redirect

Before we migrate, let's get down and dirty and add a few things to our migration:

def up
  create_table :links do |t|
    t.string :in_url
    t.text :out_url
    t.integer :http_status, :default => 301 # default to :permanent
    t.timestamps
  end

  add_index :links, :in_url
end

We've added two (2) things. First, we default the HTTP Status code to 301 (permanent redirect - for more information on HTTP status codes, see W3C's documentation on HTTP status codes

Now lets run our migration:

rake db:migrate

We should probably add some validations to our simple model:

class Link < ActiveRecord::Base
  validates :in_url, :out_url, :http_status, :presence => true
  validates :in_url, :uniqueness => true
end

Here we are making sure that in_url, out_url, and the http_status fields are all present and we make sure that in_url is unique (because we can't have the same short URL point to two different links!)

Now it's time to play around a little bit. Start up the rails development server:

rails s

Play around and add some shortenings.

Cool, now onto the fun part. Let's open up the config/routes.rb file and add a default route at the very end for catching all our links:

LeavIn::Application.routes.draw do
  resources :links
  match ':in_url' => 'links#go'
end

If you refresh the page now and try a url like http://localhost:3000/t, you'll probably get a message like "No action go defined for links_controller". So let's fix that. Open up the links_controller.rb file and add the following method:

def go
  @link = Link.find_by_in_url!(params[:in_url])
  redirect_to @link.out_url, :status => @link.http_status
end

Now check it out! Links are working as expected!

There's definitely a lot more that needs to go into this project, like adding authentication, authorization, UI, etc. but I think you understand the basic idea now.