Question

I have a validation that needs to be done in controller. If it fails I need to go back to the view action back again with all values populated as it is on the page.
Is there a simple way to do that (using incoming params map).

Answer 1

This is the basic way all Rails controllers and scaffolds work. Perhaps you should try generating scaffolds?

def create
  @banner_ad = BannerAd.new(params[:banner_ad])
    if @banner_ad.save
      flash[:notice] = 'BannerAd was successfully created.'
      redirect_to :action => "show", :id => @banner_ad
    else
      render :action => "new"
    end
  end
end

I populate a @banner_ad here, attempt to save it, if it fails, I return to the form and the @banner_ad object is available to me. I then need to have a form that uses the Rails form helpers to populate the values from the object.