getting devise to return json data when signing out

Hi all,

In curl (the command line program), I can successfully log a user in
using devise:

def create
    respond_to do |format|
        format.json {
          if user_signed_in?
            return render :json => {:success => true, :errors =>
["Already logged in."]}
          end
          resource = warden.authenticate!(:scope =>
resource_name, :recall => "#{controller_path}#failure")
          return sign_in_and_redirect(resource_name, resource)
        }
     end
   end

   def sign_in_and_redirect(resource_or_scope, resource=nil)
       scope = Devise::Mapping.find_scope!(resource_or_scope)
       resource ||= resource_or_scope
       sign_in(scope, resource) unless warden.user(scope) == resource
       return render :json => { :success => true, :redirect =>
stored_location_for(scope) || after_sign_in_path_for(resource)}
   end

   def failure
       return render :json => {:success => false, :errors => ["Login
failed."]}
   end

   def logged_in
     return render :json => {:success => false, :errors => ["Already
logged in."]}
   end

However, once they are logged in, they are never logged out. So I want
to be able to log out via curl and return json (curl is my testing
devise right now, but ultimately I intend this to work through the
iphone).

I add this to users/session controller:

def destroy
     respond_to do |format|
       format.json {
         return sign_out_and_redirect(resource_or_scope)
       }
     end
   end

   def sign_out_and_redirect(resource_or_scope)
       scope = Devise::Mapping.find_scope!(resource_or_scope)
       if Devise.sign_out_all_scopes
         sign_out_all_scopes
       else
         sign_out(scope)
       end
       return render :json => {:status => :signed_out}
     end

I get a "udefined method or variable resource_or_scope". The problem
is if i define this sign_out_and_redirect method in the application
controller, as another forum recommended:

http://stackoverflow.com/questions/4522069/rails-3-devise-how-to-get-devise-to-respond-with-json

it never gets called when I do: http://localhost:3000/users/sign_out.json.
And no json data is ever returned.

And through curl, a strange thing happens with this:

curl -X POST http://localhost:3000/users/sign_out.json -d ''

it says no route for "users/sign_out", which is odd it says that,
since users/sign_out gets invoked fine on html page.

thanks for response

I also asked this on stackoverflow:
http://stackoverflow.com/questions/7997009/rails-3-getting-devise-to-return-json-data-when-signing-out

I am finding it difficult to resolve this issue.