Question

Why controllers are named “users_controller.rb” and models are not named “user_model.rb”?

Why there is “application_controller.rb” but inside views the folder “layout” is not named “application”?

Answer 1

Code flows from thought best when the naming supports the developers internal model of the problem. When building an application, I don’t think of finding a user model (UserModel.find) I think of finding a user (User.find). On the other hand, the controllers are the translation layer between the web interface and the data store (and business logic), so it makes more sense to call them something different.

There’s also the problem of namespacing; if both my model and controller are named User, then which User am I referring to at any given moment? In this case, either you name everything with their type, which runs into the problem I describe above, or one ‘wins’ and is allowed to be referenced ‘bare’. It seems to make the most sense that the model would win, so as to provide a better mental mapping.

Inside app/views/layout is application.html.erb and you can have other layouts which are selected by different controllers.

In the end, however, these were choices made during the development of Rails, and they are entirely stylistic choices based on what the developers thought made the most sense, so there isn’t really a ‘right’ answer to your question, unfortunately. In fact, some similar decisions have been revisited. (application_controller.rb used to just be named application.rb.)