Emit JSON error output instead of HTML for JSON requests

Question

My team is using a hypermedia API built on top of collection+JSON using our modified collection+JSON gem. We would prefer to see this when there is an error and the request format is JSON:

{
   collection:
   {
      error:
      {
         'title': 'Application Error',
         'message': 'Sorry, we can't process your request at this time',
         'code': 500
      }
   }
}

instead of this, which can be hard for JSON parsers to handle:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <title>Action Controller: Exception caught</title>
  <style>
    body {
      background-color: #FAFAFA;
      color: #333;
      margin: 0px;
    }

I know how to do that using Rails' rescue_from in the ApplicationController:

class ApplicationController < ActionController::Base
  rescue_from ActionController::UnpermittedParameters, with: :bad_parameters
  rescue_from Exception, with: :exception_handling

  def bad_parameters
    respond_to do |format|
      format.html do
        if( request_is_local )
          # render helpful stack trace and stuff
        else
          render :file => 'public/404.html', :status => :not_found, :layout => false
        end
      end
      format.json { render :json => BadParametersEndpoint.new(:context => self).to_json, :status => :not_found }
    end
  end


  def exception_handling(exception)
    respond_to do |format|
      format.xml  { render :xml  => '<xml><error>Whatever</error></xml>', :status => 500 }
      format.json { render :json => ExceptionEndpoint.new(:exception => exception), :status => 500 }
      format.html do
        if( Rails.env == 'development' ) # there must be a better test ... 
                                         # somehow using config.consider_all_requests_local
          # render helpful stack trace and stuff
        else
          render :file => 'public/500.html', :status => 500, :layout => false
        end
      end
    end
  end
end

But if I do that, how do I keep the handy HTML view provided by Rails or, better yet, the one provided by a gem like better_errors?

Would rethrowing the exception work? – Sebastian Wramba May 19 '14 at 19:12 — Sebastian Wramba, May 19 '14 at 19:12

score 0 · Answer 1 · answered Aug 11 '17 at 20:13

It seems like you have not configured your rails app to be api only.

For doing the same you must add config.api_only = true line in config/application.rb file

Example:-

In config/application.rb file

module CustomApi
  class Application < Rails::Application
  config.load_defaults 5.1
  config.api_only = true
  config.time_zone = 'UTC'
 end
end

Emit JSON error output instead of HTML for JSON requests

1 Answers1