Rails 3 - Restricting formats for action in resource routes

Question

I have a resource defined in my routes.

resources :categories

And I have the following in my Category controller:

  def show
    @category = Category.find(params[:id])

    respond_to do |format|
      format.json { render :json => @category }
      format.xml  { render :xml => @category }
    end
  end

The controller action works fine for json and xml. However I do NOT want the controller to respond to html format requests. How can I only allow json and xml? This should only happen in the show action.

What is the best way to achieve this? Also is there any good tips for DRYing up the respond_to block?

Thanks for your help.

score 41 · Accepted Answer · answered Feb 15 '11 at 09:20

41

I found that this seemed to work (thanks to @Pan for pointing me in the right direction):

resources :categories, :except => [:show]
resources :categories, :only => [:show], :defaults => { :format => 'json' }

The above seems to force the router into serving a format-less request, to the show action, as json by default.

answered Feb 15 '11 at 09:20

Mike

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This will still respond with the html template if the .html extension is added to the url. – jwarzech May 15 '12 at 15:36
1

this will not limit requests to those formats, see my answer below for the correct implementation – koonse Feb 06 '13 at 07:33

score 37 · Answer 2 · edited May 23 '17 at 10:29

37

You must wrap those routes in a scope if you want to restrict them to a specific format (e.g. html or json). Constraints unfortunately don't work as expected in this case.

This is an example of such a block...

scope :format => true, :constraints => { :format => 'json' } do
  get '/bar' => "bar#index_with_json"
end

More information can be found here: https://github.com/rails/rails/issues/5548

This answer is copied from my previous answer here..

Rails Routes - Limiting the available formats for a resource

edited May 23 '17 at 10:29

Community

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answered Oct 08 '12 at 22:45

koonse

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Only "constraints" or "defaults" doesn't work for me, this answer is right. – Andrey Artemyev Mar 11 '16 at 00:03

Pan Thomakos · Answer 3 · 2011-02-14T23:06:40.040

24

You could do the following in your routes.rb file to make sure that only the show action is constrained to json or xml:

resources :categories, :except => [:show]
resources :categories, :only => [:show], :constraints => {:format => /(json|xml)/}

If this doesn't work you could try explicitly matching the action:

resources :categories, :except => [:show]
match 'categories/:id.:format' => 'categories#show', :constraints => {:format => /(json|xml)/}

edited Feb 14 '11 at 23:06

answered Feb 14 '11 at 22:13

Pan Thomakos

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Sorry, this didn't appear to work. Requesting an html page still responds. – Mike Feb 14 '11 at 22:34
I added another more explicit alternative if the first option doesn't work for you. – Pan Thomakos Feb 14 '11 at 23:06
The reason why the first part of this answer doesn't work, is that while it constrains the format it doesn't require that it be present. koonse's answer is better. – Pathogen Jun 13 '15 at 17:00

score 0 · Answer 4 · answered Jul 17 '16 at 00:37

constraints was not working for POST requests and then I tried defaults it works for all.

namespace :api, :defaults => { :format => 'json' } do
    namespace :v1 do
      resources :users do
        collection do
          get 'profile'
        end
      end
      post 'signup' => 'users#create'
      post 'login' => 'user_sessions#create'
  end
end

I was using Rails 4.2.7

Rails 3 - Restricting formats for action in resource routes

4 Answers4

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