The use of :alert (or :notice) with the render method, from the Ruby On Rails guide called 'Layouts and Rendering in Rails', does not work for me:

I'm confused as to why that Rails Guide mentions using flash values in render, since they only appear to work in redirect_to at the moment. I think you'll find your approach works if you put a flash.now[:alert] = 'Alert message!' before your render method call.

Edit: this is a flaw in the guides that will be fixed, you should use the separate method call to set the flash prior to calling render.

Try

  def bye    @counter  = 4    flash.now[:error] = "Your book was not found"    render :index  end

Normally you would do something like:

if @user.save  redirect_to users_path, :notice => "User saved"else  flash[:alert] = "You haz errors!"  render :action => :newend

What you want to do is (and I like this syntax much better):

if @user.save  redirect_to users_path, :notice => "User saved"else  render :action => :new, :alert => "You haz errors!"end

...however, that isn't valid for ActionController::Flash#render.

But, you can extend ActionController::Flash#render to do exactly what you want:

Create config/initializers/flash_renderer.rb with the following content:

module ActionController  module Flash    def render(*args)      options = args.last.is_a?(Hash) ? args.last : {}      if alert = options.delete(:alert)        flash[:alert] = alert      end      if notice = options.delete(:notice)        flash[:notice] = notice      end      if other = options.delete(:flash)        flash.update(other)      end      super(*args)    end  endend

Ref: http://www.perfectline.co/blog/2011/11/adding-flash-message-capability-to-your-render-calls-in-rails-3/