Question

I am trying to use Spree with my RoR application. Ok, I do follow all those guides and FAQs on official website when I want to customize something. That’s ok and no problem with it. One question, to which I could not find a clue — how is that possible, that there is nothing in apps/view, apps/models folders, but it’s still working? I mean, yes, I can create something in these folders and redefine the behavior of my views (actually, this is one of the ways of customization), but I really want to understand the internals. I am pretty new to Rails and got used to classic app folder structure.

Answer 1

what you are wondering about is the magic of Rails Engines.

Ruby on Rails allows you to define Engines (your app is one too) and when it looks for views/controllers/etc.. all mounted engines are part of the search path.

So the view is inside the Spree gem, not visible to you – but it still looks in there.
If you put something in your view folder with the same name, it will take precedence over the views in the Rails engine you have in the Gem.

Here is a good guide on how Engines work in Rails:

http://edgeguides.rubyonrails.org/engines.html

One good example of these Engines is the jQuery-rails Gem you probably use inside your Application.
It has no code at all (except for some fallbacks for Rails 3.0 and below that don’t have an asset pipeline), but the jQuery.js file in the app/assets/javascripts folder. And since the engine is in the load path you can require the asset that’s in there..
The engine itself has the same folder structure as your app (app/views, app/controllers …)

You can look at the internal structure of Spree here: https://github.com/spree/spree/tree/master/core/app