Hibernate version: 2.0.3

I have a User class and a Permission class, both are entities. When I update a User's Set of Permissions in the GUI, I need to delete the old Permissions set and insert the new one. I'm using synthetic ids for both.
I gave up on finding how to use cascade for this scenario. I spent 2 days reading resources (user reference, forums, etc), I could never make it work. I tried delete/insert Permissions explicitely but cascades still got in the way.
So I decided to set cascade="none" in the Set mapping of the parent, User. However I get the following exception:

1) testUpdatePermissions(com.yellowasp.usad.dao.UserDAOTest)net.sf.hibernate.HibernateException: Flush during cascade is dangerous - this might occur if an object was deleted and then re-saved by cascade
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2001)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:589)
at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1187)
at net.sf.hibernate.engine.Cascades$3.cascade(Cascades.java:88)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:258)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:298)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:341)
at net.sf.hibernate.impl.SessionImpl.preFlushEntities(SessionImpl.java:2285)
at net.sf.hibernate.impl.SessionImpl.flushEverything(SessionImpl.java:2015)
at net.sf.hibernate.impl.SessionImpl.flush(SessionImpl.java:2004)
at com.yellowasp.usad.dao.UserDAO.updatePermissions(UserDAO.java:136)
at com.yellowasp.usad.dao.UserDAOTest.testUpdatePermissions(UserDAOTest.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at com.yellowasp.usad.dao.UserDAOTest.main(UserDAOTest.java:33)

Why do I get a cascade-related error when I set it to none? My mappings:

<hibernate-mapping>

<class name="com.yellowasp.usad.User" table="T_User" >
<id name="id" >
<generator class="native" />
</id>
<property name="firstName" length="20" />
<property name="lastName" length="20" />
<property name="userName" length="20" unique="true" />
<property name="password" length="20"/>
<property name="status" type="com.yellowasp.usad.UserStatus" />

<set name="permissions"
inverse="true"
cascade="none" >
<key column="owner" />
<one-to-many class="com.yellowasp.usad.UserPerm" />
</set>
</class>
</hibernate-mapping>

<hibernate-mapping>
<class name="com.yellowasp.usad.UserPerm" table="T_UserPerm" >
<id name="id" >
<generator class="native" />
</id>
<many-to-one
name="owner" cascade="none"
class="com.yellowasp.usad.User"
not-null="true"
/>
<many-to-one
name="zone"
class="com.yellowasp.usad.UserZone"
/>
<property name="level" type="com.yellowasp.usad.PermLevel" />
</class>

<class name="com.yellowasp.usad.UserGroupPerm" table="T_UserGroupPerm" >
<id name="id" >
<generator class="native" />
</id>
<many-to-one
name="owner"
class="com.yellowasp.usad.UserGroup"
/>
<many-to-one
name="zone"
class="com.yellowasp.usad.UserZone"
/>
<property name="level" type="com.yellowasp.usad.PermLevel" />
</class>
</hibernate-mapping>

In frustration I added cascade="none" in the Child mapping as well, which of course didn't make any difference.

My code:
// load Hibernate collection type
user = (User) session.load(User.class, user.getId());

// delete children
java.util.Iterator it = user.getPermissions().iterator();
while ( it.hasNext() ) {
Permission p = (Permission) it.next();
p.setOwner(null);
session.delete(p);
}
// update parent
user.getPermissions().clear();

session.flush();

Just a random suggestion from a random forum member: try removing the cascade attribute altogether. I am not sure what cascade="none" does but I do know that leaving the attribute off does not cascade!

Cheers
Rob

You're not showing the right code.
Permission is not mapped.

cascade="none" is the default value.

Sorry, here it is. UserPerm extends Permission without adding anything, it's just a marker to distinguish between user permissions and user group permissions (UserGroupPerm). I'm not showing UserGroup for clarity.

<class name="com.yellowasp.usad.UserPerm" table="T_UserPerm" >
<id name="id" >
<generator class="native" />
</id>
<many-to-one
name="owner"
class="com.yellowasp.usad.User"
not-null="true"
cascade="none"
/>
<many-to-one
name="zone"
class="com.yellowasp.usad.UserZone"
not-null="true"
/>
<property name="level" type="com.yellowasp.usad.PermLevel" />
</class>