Hibernate - Using Join table - one-to-many association - Lazy Exception

[Gilbert johnson]

Hello,
First of all - want to thank everyone who contributes in this forum. It has helped me immensely so many times when I have been stuck.

Right now I am on my quest to learn hibernate and have already asked questions here before.

I have two tables - Group and Product which have a bi-directional many-to-many relationship. A group can have many products and a product can belong to many groups.

So I introduced a join table "Group_Product" - now this table has an extra column userID. So one of the members of this forum suggested two approaches - and I went with the approach of using two one-to-many associations. Everything is working fine.

Now I want to retrieve all products that belong to a particular Group.
In my Java Code - using groupId, I'm loading the Group object.
From my Group object - I'm getting a set of GroupProduct.
Now GroupProduct has objects Group and Product and userId as members.

Now in my java code, I have:

Iterator<GroupProduct> it = group.getGroupProducts().iterator();
while (it.hasNext())
{
   GroupProduct p = (GroupProduct)it.next();
   System.out.println("user id==="+p.getUserId());
   System.out.println("product id==="+p.getProduct().getId());
   System.out.println("product name==="+p.getProduct().getProductName());
}

The code is printing userID and productID but throws an exception while printing productName.

org.hibernate.LazyInitializationException: could not initialize proxy - no Session

I know thats because, its only querying Group and Group_Product table. Its not linking Group_Product table with Product table.

What am I missing. Really appreciate your responses.
Thanks

Here are my hbm.xml files
Group.hbm.xml

<id name="id" column="ID"><generator class="increment"/></id>
<set name="groupProducts" table="GROUP_PRODUCT" lazy="false">
    <key column="GROUPID"/>
    <one-to-many class="qwicket.myapp.model.GroupProduct"/>   
</set>

GroupProduct.hbm.xml

<id name="id" column="ID"><generator class="increment"/></id>
<property name="userId" column="userId"/>
<many-to-one name="group" column="groupId" class="qwicket.myapp.model.Group" not-null="true"/>
<many-to-one name="product" column="productId" class="qwicket.myapp.model.Product" not-null="true"/>

Product.hbm.xml

<id name="id" column="ID"><generator class="increment"/></id>
<property name="productName" column="PRODUCTNAME"/>
<property name="description" column="DESCRIPTION"/>
<set name="groupProducts" table="GROUP_PRODUCT" lazy="false">
   <key column="PRODUCTID"/>
   <one-to-many class="qwicket.myapp.model.GroupProduct"/>   
</set>

[ March 26, 2008: Message edited by: Gilbert johnson ]

[Mark Spritzler]

LazyInitializationExceptions occur when Hibernate tries to get data from the database, but there is no longer a Session open. Basically, where you are trying to access the other data Hibernate wants to run a query against the database, but it can't get a Connection to the database, which it gets from the Session object, which is no longer open or available.

Mark