Rails - Feb 2007 - 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'' %>

<!--[form:item]-->
<p><label for="item_title">Title</label><br/>
<%= text_field ''item'', ''title'' 
%></p>

<p><label for="item_link">Link</label><br/>
<%= text_field ''item'', ''link'' 
%></p>

<p><label
for="item_description">Description</label><br/>
<%= text_area ''item'', ''description'' 
%></p>

<!--[eoform:item]-->


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?


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