Difference between resource and resources methods

Question

What is the logical difference between resource and resources methods

Here is some examples:

resource :orders, :only => [:index, :create, :show]  > rake routes  orders POST       /orders(.:format)            orders#create         GET        /orders(.:format)            orders#show   resources :orders, :only => [:index, :create, :show]  > rake routes  orders GET        /orders(.:format)            orders#index         POST       /orders(.:format)            orders#create   order GET        /orders/:id(.:format)        orders#show   resource :orders  > rake routes      orders POST       /orders(.:format)            orders#create  new_orders GET        /orders/new(.:format)        orders#new edit_orders GET        /orders/edit(.:format)       orders#edit             GET        /orders(.:format)            orders#show             PUT        /orders(.:format)            orders#update             DELETE     /orders(.:format)            orders#destroy   resources :orders  > rake routes      orders GET        /orders(.:format)            orders#index             POST       /orders(.:format)            orders#create   new_order GET        /orders/new(.:format)        orders#new  edit_order GET        /orders/:id/edit(.:format)   orders#edit       order GET        /orders/:id(.:format)        orders#show             PUT        /orders/:id(.:format)        orders#update             DELETE     /orders/:id(.:format)        orders#destroy 

It looks like method resource does not create route for index, and helpers in some cases are different (new_order and new_orders). Why?

Answer 1

At a high level, the intent of resource is to declare that only one of these resources will ever exist. For example:

resource :profile, :only => [:edit, :update] 

As a user, I should only be able to update my own profile. I should never be able to edit other users' profiles, so there's no need for a URL scheme like /users/1/profile/edit. Instead, I use /profile/edit, and the controller knows to use the current user's ID rather than the ID passed in the URL (since there is none).

That's why you don't get an index action with resource: there's only one resource, so there's no sense in "listing" them.

Answer 2

Actually you are right, resource should not create an index action, unless you ask for the index action explicitly, this way:

resource :orders, :only => [:index, :create, :show] 

Helpers should differ too, but not that much as in your example, because the convention is to use a singular form with the resource method, and the plural with the resources

resources :orders => rake routes       orders GET        /orders(.:format)            orders#index             POST       /orders(.:format)            orders#create   new_order GET        /orders/new(.:format)        orders#new  edit_order GET        /orders/:id/edit(.:format)   orders#edit       order GET        /orders/:id(.:format)        orders#show             PUT        /orders/:id(.:format)        orders#update             DELETE     /orders/:id(.:format)        orders#destroy  resource :order => rake routes       order POST       /order(.:format)            orders#create   new_order GET        /order/new(.:format)        orders#new  edit_order GET        /order/:id/edit(.:format)   orders#edit             GET        /order/:id(.:format)        orders#show             PUT        /order/:id(.:format)        orders#update             DELETE     /order/:id(.:format)        orders#destroy 

And the logical difference is to declare you logically can't have the plural for resource in your app, for example Admin or whatever