title: use case for getProductAdditionalInformationBlock in magento
body: <p>I'd like to put some additional info under each item in the cart. I have this info already saved in table "sales_flat_quote_item" in "additional_info" field. So the question is only how to show it globally at all places where the items are shown.</p>
  
  <p>I saw in several places under item name there is a structure like this:</p>
  
  <pre><code>&lt;?php if ($addtInfoBlock = $this-&gt;getProductAdditionalInformationBlock()):?&gt;
   &lt;?php echo $addtInfoBlock-&gt;setItem($_item)-&gt;toHtml() ?&gt;
  &lt;?php endif;?&gt;
  </code></pre>
  
  <p>For example in this files:
  /app/design/frontend/base/default/template/checkout/cart/item/default.phtml
  /app/design/frontend/base/default/template/checkout/onepage/review/item.phtml</p>
  
  <p>So I suppose this is the place I should use for such task.</p>
  
  <p>What I figured out is that:
  I have to add my own block definition to for example:</p>
  
  <pre><code>&lt;checkout_cart_index&gt;
    &lt;block type="core/text_list" name="additional.product.info" translate="label"&gt;
    &lt;label&gt;Additional Product Info&lt;/label&gt;
    &lt;block type="various/itemrendererdefault" name="glass.additional" as="glass"    template="checkout/cart/glass_additional.phtml"/&gt;
    &lt;/block&gt;
  &lt;/checkout_cart_index&gt;
  </code></pre>
  
  <p>This is no problem so far. My class is loaded </p>
  
  <pre><code>class Site1_Various_Block_Itemrendererdefault extends Mage_Core_Block_Template {
  
  public function setItem(Varien_Object $item) {
      $this-&gt;setData('item', $item);
      return $this;
  }
  
  public function getItem() {
      return $this-&gt;_getData('item');
  }
  
  }
  </code></pre>
  
  <p>and the template  checkout/cart/glass_additional.phtml is called. </p>
  
  <p>But inside the template I have no idea how to get the info about what $item should I process. I tried:</p>
  
  <pre><code>$_item = $this-&gt;getItem();
  print_r($_item);
  $_item = $this-&gt;getData();
  print_r($_item);
  </code></pre>
  
  <p>but it returns nothing.</p>
  
  <p>So my question is: How to get $item data inside my template. 
  Can I access the data set in?</p>
  
  <pre><code>...
  $addtInfoBlock-&gt;setItem($_item)-&gt;toHtml();
  ...
  </code></pre>