My attempt at validation

_form.erb

<ul>
  <li><%= f.label :name %>: <%= f.text_field :name %></li>
	<li><%= f.label :url %>: <%= f.text_field :url, :size => 100 %></li>
  <li><%= f.label :quantity %>: <%= f.text_field :quantity %></li>
  <li><%= f.label :price %>: <%= f.text_field :price %></li>
  <li><%= f.label :weight %>: <%= f.text_field :weight %></li>
  <li><%= f.label :description %>: <%= f.text_area :itemDescription %></li>
</ul>

edit.html.erb

<% form_for @item, { :url => user_character_item_url(@user, @character, @item.id) } do |f| %>
  <%= render :partial => 'form', :locals => { :f => f } %>
  <%= "<iframe src=\"#{@item.url}\"></iframe>" if not @item.url.empty? %>
  <div id="navigation">
    <%= link_to image_tag('back.png'), user_character_url(@user, @character, { :section => 'items' }) %>
    <%= image_submit_tag 'update.png', :class => 'submit' %>
  </div>
<% end %>

item.rb

class Item < ActiveRecord::Base
  belongs_to :character
  has_friendly_id :name, :use_slug => true, :scope => :character
  validates_presence_of :name, :quantity
end

items_controller.rb

class ItemsController < ApplicationController

  def new
    @user = User.find(params[:user_id])
    @character = @user.characters.find(params[:character_id])
    @item = @character.items.new
  end

  def create
    @user = User.find(params[:user_id])
    @character = @user.characters.find(params[:character_id])
    @item = @character.items.new(params[:item])

    if @item.save
      flash[:pass] = "Item \"#{@item.name}\" was successfully created."
      redirect_to user_character_url(@user, @character, { :section => 'items' })
    else
      flash[:fail] = 'Item creation failed.'
      render :action => "new"
    end
  end

  def edit
    @user = User.find(params[:user_id])
    @character = @user.characters.find(params[:character_id])
    @item = @character.items.find(params[:id])
  end

  def update
    @user = User.find(params[:user_id])
    @character = @user.characters.find(params[:character_id])
    @item = @character.items.find(params[:id])
    RAILS_DEFAULT_LOGGER.info("PARAMS: #{params[:item]}")
    if @item.update_attributes(params[:item])
      flash[:pass] = "Item \"#{@item.name}\" successfully updated."
      redirect_to user_character_url(@user, @character, { :section => 'items' })
    else
      flash[:fail] = "Item update failed.#{@item.errors} test"
      render :action => 'edit'
    end
  end

  def destroy
    @user = User.find(params[:user_id])
    @character = @user.characters.find(params[:character_id])
    @item = @character.items.find(params[:id])
  
    if @item.destroy
      flash[:pass] = "Item \"#{@item.name}\" successfully deleted."
    else
      flash[:fail] = 'Item deletion failed.'
    end
    redirect_to user_character_url(@user, @character, { :section => 'items' })
  end

end

Log

 SQL (0.3ms)   SET NAMES 'utf8'
  SQL (0.2ms)   SET SQL_AUTO_IS_NULL=0
  Item Columns (8.7ms)   SHOW FIELDS FROM `items`
  Item Load (0.3ms)   SELECT * FROM `items` WHERE (`items`.`id` = 50568) LIMIT 1
  SQL (0.1ms)   BEGIN
  SQL (0.1ms)   ROLLBACK
DEPRECATION WARNING: Giving :session_key to SessionStore is deprecated, please use :key instead. (called from new at /opt/local/lib/ruby/gems/1.8/gems/actionpack-2.3.11/lib/action_controller/middleware_stack.rb:72)
  SQL (0.1ms)   SET NAMES 'utf8'
  SQL (0.1ms)   SET SQL_AUTO_IS_NULL=0


Processing ItemsController#update (for 127.0.0.1 at 2012-02-12 10:46:26) [PUT]
  Parameters: {"x"=>"82", "y"=>"18", "authenticity_token"=>"Q9BAA8LaWOnSCy5WIW2tDiQKvKJzMbcSYv0tvO/ZdY0=", "id"=>"50568", "user_id"=>"mpatteegmailcom", "character_id"=>"20370", "item"=>{"price"=>"", "name"=>"New Item", "itemDescription"=>"", "quantity"=>"", "weight"=>"", "url"=>""}}
  User Columns (4.2ms)   SHOW FIELDS FROM `users`
  User Load (0.5ms)   SELECT `users`.* FROM `users` INNER JOIN `slugs` ON `slugs`.sluggable_id = `users`.id AND `slugs`.sluggable_type = 'User' WHERE (`slugs`.`sequence` = 1 AND `slugs`.`name` = 'mpatteegmailcom') LIMIT 1
  Character Columns (2.1ms)   SHOW FIELDS FROM `characters`
  Character Load (0.3ms)   SELECT * FROM `characters` WHERE (`characters`.`id` = 20370 AND (`characters`.user_id = 1)) 
  Item Load (14.8ms)   SELECT `items`.* FROM `items` INNER JOIN `slugs` ON `slugs`.sluggable_id = `items`.id AND `slugs`.sluggable_type = 'Item' WHERE (`items`.character_id = 20370) AND ((`slugs`.`scope` IS NULL AND `slugs`.`sequence` = 1 AND `slugs`.`name` = '50568')) ORDER BY name LIMIT 1
  Item Columns (0.9ms)   SHOW FIELDS FROM `items`
  Item Load (0.2ms)   SELECT * FROM `items` WHERE (`items`.`id` = 50568 AND (`items`.character_id = 20370)) ORDER BY name LIMIT 1
PARAMS: nameNew ItempricequantityitemDescriptionurlweight
  SQL (0.1ms)   BEGIN
  SQL (0.1ms)   ROLLBACK
Rendering template within layouts/application
Rendering items/edit
  Slug Load (0.3ms)   SELECT * FROM `slugs` WHERE (`slugs`.sluggable_id = 1 AND `slugs`.sluggable_type = 'User') ORDER BY id DESC LIMIT 1
Rendered items/_form (102.5ms)
Completed in 224ms (View: 122, DB: 24) | 200 OK [http://localhost/users/mpatteegmailcom/characters/20370/items/50568]