public   class  CartForm  extends  ValidatorForm
{
	 private  List disks =  new  LinkedList();
	 public  List getDisks() {
		 return  disks;
	}
	 public   void  setDisks(List disks) {
		 this .disks =(LinkedList) disks;
	}
}

 public   class  CartItemBean  implements  Serializable {
    private  DiskBean disk;
    private   int  quantity;

    public  CartItemBean( DiskBean diskAdd,  int  number )
   {
      disk = diskAdd;
      quantity = number;
   }
    public  DiskBean getDisk()
   {
       return  disk;
   }
    public   void  setQuantity(  int  number )
   {     
     quantity = number;
   }
    public   int  getQuantity()
   {
       return  quantity;
   }
}

<form name="cartForm"> 
    <field property="quantity" indexedListProperty="disks" depends="validwhen">
     	<arg key="javascript.nomerdiska.registr"/>
       	<var>
          <var-name>test</var-name>
	  <var-value>((disks[].quantity > 0 ) or (*this* != null))</var-value>
        </var>
    </field>	
</form>

<logic:iterate id="disks" name="cartForm" property="disks" indexId="index" >
 <html:text name="disks" property="quantity" indexed="true" size="10" />
</logic:iterate>