Acts_as_list and validations

I start out with this:

MODEL

class Item < ActiveRecord::Base
validates_presence_of :title, :description, :link
end

CONTROLLER

class ItemController < ApplicationController

other actions here…

def create
@item = Item.new(params[:item])
if @item.save
flash[:notice] = ‘Item was successfully created.’
redirect_to :action => ‘list’
else
render :action => ‘new’
end
end
end

FORM

<%= error_messages_for ‘item’ %>

Title
<%= text_field 'item', 'title' %>

Link
<%= text_field 'item', 'link' %>

Description
<%= text_area 'item', 'description' %>

So, if any of title/descripton/link are missing when I create an Item,
the new page is re-rendered with a nice set of error messages.

However, I next create a list consisting of a feed (parent) with
multiple children (items) using acts_as_list. The model code for Item
now looks like this:

MODEL

class Item < ActiveRecord::Base
belongs_to :feed
acts_as_list :scope => :feed_id
validates_presence_of :title, :description, :link
end

For the controller, I tried several things but nothing quite works.

CONTROLLER SCENARIO #1

def create
feed = Feed.find(session[:current_feed_id])
if feed.items.create(params[:item])
flash[:notice] = ‘Item was successfully created.’
redirect_to :action => ‘list’
else
render :action => ‘new’
end

This is fine if everything validates. The item is created
successfully, all the acts_as_list columns are in synch.

But (as I discovered) create essentially returns true whether
validation fails or not. So the if test is useless. This can also be
verified by using the bang version of create (create!). In that case,
an exception is thrown and the exception messages indeed indicate all
the validation violations.

Given this, I next tried the following:

CONTROLLER SCENARIO #2 (create!)

def create
feed = Feed.find(session[:current_feed_id])
begin
feed.items.create!(params[:item])
flash[:notice] = ‘Item was successfully created.’
redirect_to :action => ‘list’
rescue
render :action => ‘new’
end

This code catches validation exceptions correctly, The ‘new’ page was,
in fact, be re-rendered but alas, no error messages.

I didn’t look at the validation code before doing this (probably
should have). But I was hoping that the error message packaging for
the forms (<%= error_messages_for ‘item’ %>) was synched with
exceptions since the messages were the same.

I could, I suppose, catch the errors in ‘rescue’ and put out my own
error messages but I can’t help but think that I’m just missing
something here since this must be a fairly common occurrence.

Any ideas?