Rails 4 - How to render JSON regardless of requested format?

Question

I'd like a Rails controller (all of them, actually, it's an API) to render JSON always always.

I don't want Rails to return "route not found", or try and fail to find an HTML template, or return 406. I just want it to automatically and always render JSON, e.g. from a RABL or JBuilder view.

Is this possible? Related questions seem to have answers that have the aforementioned downsides.

score 50 · Accepted Answer · answered May 30 '14 at 03:49

50

You can add a before_filter in your controller to set the request format to json:

# app/controllers/foos_controller.rb

before_action :set_default_response_format

protected

def set_default_response_format
  request.format = :json
end

This will set all response format to json. If you want to allow other formats, you could check for the presence of format parameter when setting request.format, for e.g:

def set_default_response_format
  request.format = :json unless params[:format]
end

answered May 30 '14 at 03:49

vee

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Naturally, this can be placed in `/app/controllers/application_controller.rb` to have an application-wide effect (strictly if your app is an API) – Epigene Jan 22 '16 at 10:33
FWIW, I just tried this solution in Rails 5 (with html format, vs json) and Rails wouldn't take `:html`, it needed `'html'` as a string. Not sure why it wouldn't accept a symbol for `request.format`, but once I changed it to `'html'` from `:html` it worked great. – BJ Miller Nov 23 '16 at 15:57
in rails 5 I use `request.format = :json unless request.format.symbol` – akostadinov Dec 02 '16 at 14:50
or inline it: ``` before_action { request.format = :json unless request.format } ``` – Ákos Vandra-Meyer Sep 11 '20 at 08:28

score 13 · Answer 2 · answered Oct 01 '14 at 20:12

13

You can use format.any:

def action
  respond_to do |format|
    format.any { render json: your_json, content_type: 'application/json' }
  end
end

answered Oct 01 '14 at 20:12

Peleg

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score 5 · Answer 3 · answered Aug 17 '19 at 17:17

5

It's just:

render formats: :json

answered Aug 17 '19 at 17:17

Artem P

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@Akaisteph7 Not quite sure what you mean. This answer is clearly different from other. – Artem P Aug 18 '19 at 09:43
What I mean is that you should add some context to your answer. – Akaisteph7 Aug 18 '19 at 18:46

score 0 · Answer 4 · answered Dec 06 '16 at 17:37

0

I had similar issue but with '.js' extension. To solve I did the following in the view: <%= params.except!(:format) %> <%= will_paginate @posts %>

answered Dec 06 '16 at 17:37

ruslan

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7

score 0 · Answer 5 · answered Oct 09 '20 at 22:53

I tried the above solutions and it didn't solve my use case. In some of the controllers of my Rails 4.2 app, there was no explicit render called. For example, a service object was called and nothing was returned. Since they are json api controllers, rails was complaining with a missing template error. To resolve I added this to our base controller.

  def render(*args)
    options = args.first
    options.present? ? super : super(json: {}, status: :ok)
  end

It's a large app I'm converting to Rails 5, so this is just a safety measure as I removed the RocketPants gem that seemed to do this automatically.

As a note, my controllers inherit from ActionController::Base

score -1 · Answer 6 · answered May 30 '14 at 03:48

-1

Of course:

before_filter :always_json

protected

def always_json
  params[:format] = "json"
end

You should probably put this in a root controller for your API.

answered May 30 '14 at 03:48

Maurício Linhares

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Rails 4 - How to render JSON regardless of requested format?

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