I have checked the forums, and it appears that this question props up on a regular basis. However, I am unable to find an answer that applies to my case. Any help is greatly appreciated.

****** java code *****
public class Main
{
private SessionFactory factory;

public void populate() throws Exception
{
// open a session and save the team
Session s = null;
Transaction tx = null;
try
{
s = factory.openSession();
tx = s.beginTransaction();

User user = new User();
user.setLoginName("name");
user.setFirstName("First");
user.setLastName("Last");

Set emails = new Set();
Email email = new Email();
email.setEmail("[email protected]");
------exception--> emails.add(email);

//user.setEmails(emails);

s.saveOrUpdate(user);
tx.commit();
}
catch (Exception e)
{
if (tx!=null) tx.rollback();
throw e;
}
finally
{
s.close();
}
}

public static void main(String[] args) throws Exception {

final Main test = new Main();

Configuration cfg = new Configuration()
.addClass(User.class)
.addClass(Email.class);

//cfg.setProperty("hibernate.show_sql", "true");

test.factory = cfg.buildSessionFactory();

test.populate();

}
}

***** users mapping *****
<hibernate-mapping
package="users">

<class name="User" table="Users" proxy="User">
<id name="id">
<generator class="native"/>
</id>
<property name="loginName" not-null="true" unique="true"/>
<property name="firstName"/>
<property name="lastName"/>

<set name="emails" cascade="all">
<key column="userid"/>
<one-to-many class="Email"/>
</set>

</class>

</hibernate-mapping>

***** emails *****
<hibernate-mapping
package="users">

<class name="Email" table="Emails">
<id name="id">
<generator class="native"/>
</id>
<property name="email" not-null="true" unique="true"/>
</class>

</hibernate-mapping>

********* Log output (partial) *****

15:08:40,330 DEBUG SessionImpl:542 - opened session
15:08:40,340 DEBUG JDBCTransaction:37 - begin
15:08:40,340 DEBUG DriverManagerConnectionProvider:84 - total checked-out connections: 0
15:08:40,340 DEBUG DriverManagerConnectionProvider:90 - using pooled JDBC connection, pool size: 0
15:08:40,350 DEBUG JDBCTransaction:41 - current autocommit status:false
15:08:40,380 ERROR LazyInitializationException:25 - Failed to lazily initialize a collection - no session or session was closed
net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed
at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:209)
at net.sf.hibernate.collection.PersistentCollection.write(PersistentCollection.java:84)
at net.sf.hibernate.collection.Set.add(Set.java:154)
at Main.populate(Main.java:49)
at Main.main(Main.java:80)
15:08:40,390 DEBUG JDBCTransaction:82 - rollback
15:08:40,390 DEBUG SessionImpl:572 - transaction completion
15:08:40,390 DEBUG SessionImpl:560 - closing session
15:08:40,390 DEBUG SessionImpl:3327 - disconnecting session
15:08:40,400 DEBUG DriverManagerConnectionProvider:120 - returning connection to pool, pool size: 1
15:08:40,400 DEBUG SessionImpl:572 - transaction completion
net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed
at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:209)
at net.sf.hibernate.collection.PersistentCollection.write(PersistentCollection.java:84)
at net.sf.hibernate.collection.Set.add(Set.java:154)
at Main.populate(Main.java:49)
at Main.main(Main.java:80)
Exception in thread "main"

i think you are accidentally using the hibernate collection set instead of the java.util.Set. check your imports.



a hibernate set collection during initlaization checks to see if it is associated with the session (this is what makes it "live").

Thank you very much. That was exactly my problem. Saved me a day of another grief!