AbstractController::DoubleRenderError in Admin

问题

I am working on spree commerce, I am trying to tweak couple of actions in the active_sale_controller. I have some conditions, if the condition fails I am redirecting_to (:back) else I am proceeding to next step. The problem I am facing right now is I have used redirected_to (:back), twice in the same action and also I have one more redirected_to to some other controller in the same action, the browser shows a error which is says

"Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like "redirect_to(...) and return"." 

here is my code

when "2"
    st_days = DateTime.strptime("#{start_date}","%d/%m/%Y %H:%M:%S")
    ed_days = DateTime.strptime("#{end_date}","%d/%m/%Y %H:%M:%S")
    ps = PoSale.where(:active_sale_id => @active_sale.id, :event_name => @taxon_name,:st_date => @start_date, :ed_date => @end_date).last
    if ((st_days >= ps.st_date and st_days <= ps.ed_date) or ( ed_days >= ps.st_date and ed_days <= ps.ed_date))   
        redirect_to (:back), :notice => "problem with the start_date and end_date"
    else
        PoSale.create(:active_sale_id => params[:id], :event_name => params[:active_sale]["taxon_name"], :st_date => DateTime.strptime("#{start_date}","%d/%m/%Y %H:%M:%S"), :ed_date => DateTime.strptime("#{end_date}","%d/%m/%Y %H:%M:%S"))
    end         
    when "3"
        puts "Inside 3"
        puts "*"*20
        #hidesd = DateTime.parse(params[:hide_start_date].split("+")[0])
        #hideed = DateTime.parse(params[:hide_end_date].split("+")[0])
        # hideed = DateTime.strptime("#{hide_end_date}","%d/%m/%Y %H:%M:%S")
        puts "*"*20
        #puts "Parameters:#{hidesd}"
        #puts hideed
        a_sale_id=params[:id].to_i
        #PoSale.where("active_sale_id = 310 and st_date = '2012-07-05 03:03:00' and ed_date ='2012-07-12 08:03:00'")
        st_days = DateTime.strptime("#{start_date}","%d/%m/%Y %H:%M:%S")
        ed_days = DateTime.strptime("#{end_date}","%d/%m/%Y %H:%M:%S")

        diff = (st_days.to_date - ed_days.to_date).to_i
        if diff > 10 
            redirect_to (:back), :notice => "more then 10 days not hapenning"      
        else
            ps = PoSale.where(:active_sale_id => a_sale_id, :event_name => @taxon_name, :st_date => @start_date, :ed_date => @end_date).last #where("active_sale_id =#{a_sale_id} and st_date like ? and ed_date like ?",hidesd.strftime("%Y-%m-%d %H:%M:%S"),hideed.strftime("%Y-%m-%d %H:%M:%S")).last #use find
            ps.update_attributes(:event_name => params[:active_sale]["taxon_name"], :st_date => DateTime.strptime("#{start_date}","%d/%m/%Y %H:%M:%S"), :ed_date => DateTime.strptime("#{end_date}","%d/%m/%Y %H:%M:%S"))
        end

Kindly help me out !!!

回答1:

redirect_to does not stop execution of the action method so if you call it and later call render or another redirect_to you will get the double render exception. There is a fairly simple fix, just call and return. e.g.

redirect_to (:back), :notice => "problem with the start_date and end_date" and return

See 'Avoiding double render exceptions' in the Rails guide.

来源：https://stackoverflow.com/questions/11590116/abstractcontrollerdoublerendererror-in-admin