Can someone please explain to me in clear, layman's terms what the deal is with mapped resources and named routes in Ruby on Rails?

Question

I've been using Ruby for the first time on a project at my work, so I am still somewhat learning the ropes (and loving every minute of it).

While I understand the point of the map.connect functions in the route.rb file, I don't understand the "resources" and "named route" features of Rails. I have my Rails book here and read it over several times, but I still don't get it. The named routes I kinda get - I think that they are either rules, either explicitly defined, or calculated by a code block, but the resources are a complete mystery to me; the only thing I've gleamed rom them is that you just NEED them if you want some of the cool stuff to work, such as being able to call 'resource_path' (and its awesome related family of methods).

My current project has:

map.resources :application_forms
map.resources :sections
map.resources :questions
map.resources :seed_answers
map.resources :question_types
map.resources :form_questions
map.resources :rules
map.resources :form_rules

..but my Rails book has this awesome kinda "has_many" and "only" type hashes and parameters hanging off them and I can't work out exactly when I am supposed to use them, nor what the benefit is.

Can anyone set me straight?

Answer 1

Named routes are just that; a route with a name attached, so that you can easily refer to it when you want to generate a URL. Among other things, it can eliminate ambiguity.

A resource is basically a 'thing' that you want to have routes to manipulate. When you define that 'sections' is a resource, what you're doing is saying "I want a route to get all the sections. I want a route to add a new section. I want a route to edit an existing section. I want a route to delete a section." That sort of thing. These routes point to standardized method names like index, new, edit, and so on. Each of these routes will have a name assigned based on what it is; so there is now a route named 'edit_section'.

The :has_many parameter lets you say that a certain kind of thing has sub-things. For example, you can say map.resources :sections, :has_many => [:questions]. This means that a question belongs to a section, and this will be reflected in the url and the route. You'd get urls like '/sections/27/questions/12' and named routes like 'section_questions'.

The :only parameter says "only make routes for these actions"; you could use it if you only want to allow listing, viewing, and adding items, not editing or deleting.

Answer 2

Honestly the Rails Routing Guide will give you a good explanation in about as plain wording as you can get. Just know that a resource route == RESTful route and you're good to go.

Answer 3

We all struggled with understanding resources and REST when DHH introduced it to the Rails community at the first RailsConf in 2006, so it is not wonder you have trouble grasping the concept.

I admit there is much better and more up-to-date explanations of the concepts today, but back then, right after David's keynote, I wrote a blog post in which I, from discussion with other conference attendees, tried to understand and explain it. It might help you, as it doesn't take for granted that you know everything about REST as more recent articles do.