Redisplay a filled form with redirect

example.rb

# In the controller

def update
  @model = Model.find params[:id]
  if @model.update_attributes(params[:model])
    redirect_to an_url 
  else
    save_for_redisplay(@model)
    redirect_to other_url
  end
end


# In the view
= form_for load_or_build_to_redisplay(:model) do
  # Normal fields

refill.rb

# In some helper
  def saved_for_redisplay?(obj)
    obj_name = ActiveRecord::Base === obj ? obj.class.model_name.underscore : obj.to_s
    flash.has_key?(:"saved_#{obj_name}_for_redisplay")
  end

  def load_or_build_to_redisplay(model_name)
    if saved_for_redisplay?(model_name)
      obj = model_name.to_s.classify.constantize.new flash[:"saved_#{model_name}_for_redisplay"]
      obj.valid?
      obj
    else
      model_name.to_s.classify.constantize.new
    end
  end


# In the controller
  def save_for_redisplay(obj)
    flash[:"saved_#{obj.class.model_name.underscore}_for_redisplay"] = obj.attributes
  end