Restricting Ruby on Rails Routes with :only and :except

2022-12-03 397 words 2 minutes

Contents

Generating All Routes for a Model

Lets say we have an item model in a Ruby on Rails application. To create standard routes for this model, we write the following in config.rb:

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Rails.application.routes.draw do
  resources :items
end

We can run rails routes to see the routes created by the code above:

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$ rails routes -c items

   Prefix Verb   URI Pattern               Controller#Action
    items GET    /items(.:format)          items#index
          POST   /items(.:format)          items#create
 new_item GET    /items/new(.:format)      items#new
edit_item GET    /items/:id/edit(.:format) items#edit
     item GET    /items/:id(.:format)      items#show
          PATCH  /items/:id(.:format)      items#update
          PUT    /items/:id(.:format)      items#update
          DELETE /items/:id(.:format)      items#destroy

What if we don’t need all of these routes though? We can use :only and :except to restrict the routes that are created for a model.

Restricting Routes with :only

If we only need a few routes, it makes sense to use :only to create only the routes we need. For example, if we only want the index and show routes, we can specify them inside an array after only::

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Rails.application.routes.draw do
  resources :items, only: [:index, :show]
end

This results in only 2 routes being created and we can verify with rails routes:

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$ rails routes -c items

Prefix Verb URI Pattern          Controller#Action
 items GET  /items(.:format)     items#index
  item GET  /items/:id(.:format) items#show

Restricting Routes with :except

:except works in the opposite way. Instead of specifying the routes we want to create, we specify the ones we don’t want to create.

If we take the example from above and replace only: with :except, we can see what happens:

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Rails.application.routes.draw do
  resources :items, except: [:index, :show]
end

This time we can see that all routes except for index and show were created:

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$ rails routes -c items

   Prefix Verb   URI Pattern               Controller#Action
    items POST   /items(.:format)          items#create
 new_item GET    /items/new(.:format)      items#new
edit_item GET    /items/:id/edit(.:format) items#edit
     item PATCH  /items/:id(.:format)      items#update
          PUT    /items/:id(.:format)      items#update
          DELETE /items/:id(.:format)      items#destroy

Restricting a Single Route

Note that if you need to restrict a single route with either :only or :except, there is no need to place the route in an array. Write it as a symbol after :only or :except like so:

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Rails.application.routes.draw do
  resources :items, except: :index
end

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Rails.application.routes.draw do
  resources :items, only: :index
end

References:

https://guides.rubyonrails.org/routing.html#restricting-the-routes-created