What Is $LOAD_PATH (also known as $:)

I have come across $LOAD_PATH many times and have always skipped over it, never quite understanding what it meant. Well, that is, until recently. The project that I am working on forced me to take a closer look. And once I did, like most things, it really wasn’t that difficult at all.

The first thing to understand is what it refers to. Quite simply $LOAD_PATH is what Ruby uses to determine which directories to look in when you use require in your code. In other words, $LOAD_PATH contains nothing more than lots of directories. Easy, huh?

The second thing you should know is how to reference it. You can refer to $LOAD_PATH in two ways. The first way is to simply call it by its name, $LOAD_PATH.

The second way is to use the predefined variable, $:

Both mean the exact same thing.

Finally to see it in action, here is an example of adding a directory to $LOAD_PATH

$: << File.expand_path('../', __FILE__)

RESTful Rails

Recently I decided to add a new download file feature to the Rails Girls Ideas app. It seemed like a straightforward task. But, upon opening the routes.rb file, I realised I there was more to this decision than I first thought. I had to decide on the type of route…should I create a member route or a resource route?

What is a Member Route

A member route simply adds an additional action to the enclosing resource.

The example below adds a new file action to the existing ideas controller (ideas_controller.rb). In this case the file relates to a single idea. The url to access it would be something like /ideas/1/file

# routes.rb

resourses :ideas do
  member do
    get :file

# ideas_controller.rb

class IdeasController < ApplicationController
  def file
   # download code here

However I started to think about what else I might need to do with the files: What if I want to add some more methods? What if I want to rename the file, or tag the file? What if I want to add a method to delete the file? And if I add all this new functionality, does it still belong in the ideas_controller?

Why a Resource Route

In order to keep controllers from becoming bloated, you can put the new action into its own controller. Then if the situation arises where you want to extend the functionality of the controller and add methods such as upload/download/rename/tag/delete actions you are already in the right place.

# routes.rb

resources :ideas do
  resource :file, only: [:show]

# creating the new method in its own controller

class FilesController < ApplicationController do
  def show
    #download method

The url to access it is still something like /ideas/1/file. The only difference lies in the fact that file is now an entity all of it’s own and, as such, has it’s own controller.

Remember when in doubt type rake routes at the command line to find your way. It will show you the http verbs, the controller and corresponding action and also the url helpers

I should point out that using a resource route is considered more RESTful than a member route. However understanding the difference is the key, as it will guide you in making an informed decision 🙂