Rails 3.2.0 - Redirecting after a JSON call is made -

i have controller action handles json requests handling datatables grid redrawing. have before_filter checks if session has been destroyed , should redirect logout action. when request ajax request, redirect happens fine. if request json, logs shows "filter chain halted :authorize rendered or redirected" not redirect page @ all. clues?

i see logs show it's processing action json:

processing usercontroller#datatable_redrawings json 

my contoller method:

before_filter :auth  def auth   if session[:username].blank?     flash[:error] = "please login."     if request.xhr?       render :js => "window.location = '/logout'"     else       respond_to |format|         format.html { redirect_to :action => "logout" }       end     end   end end 

a redirection isn't restful, nor sending js when client expecting json response. should send unauthorized (401) http status code or similar.

before_filter :auth  def auth   if session[:username].blank?     respond_to |format|       format.json { render :json => [], :status => :unauthorized }       format.html { redirect_to :action => "logout" }     end     return false   end end