nhibernate and All-delete-orphan - nhibernate

Question

i have a an entity class which has a bag of child entity class like so(copied relevant lines):
<class name="Entity" table="Entities" lazy="false">
<id name="ID">
<generator class="guid"/>
</id>
<bag name="SubEntities" table="SubEntities" cascade="all-delete-orphan">
<key column="EntityID"/>
<one-to-many class="SubEntity"/>
</bag>
</class>
Now, the mapping works well and as expected in most cases (when i delete/save it cascades), but when i try to remove some subentity(child) from the bag in the Entity(parent) class - the change does not cascade and all i see in the DB is that the subentitiy's foreign key was changed to null, and not deleted as i would like.
I've read something about nhibernate not realizing which line it needs to delete in the database (no unique id for the row) - so i tried to use the idbag instead of the bag - but the idbag does not allow a one-to-many collection in it, i've tried something of the sort:
<idbag name="SubEntities" table="SubEntities" cascade="all-delete-orphan">
<collection-id column="Id" type="Guid">
<generator class="guid"/>
</collection-id>
<key column="EntityID"/>
<one-to-many class="SubEntity"/>
</idbag>
which of course gives the error that one-to-many isnt allowed there.
Even when i try to use the component (which i dont want as i want the child is also an entity) - i cant use an external hbm file to define it (the subentity is a rather large class by itself)
so setting the entity's propertise in the parent's hbm files isnt a good idea as well.
Could anyone help me out with explaning whats wrong and how am i supposed to fix it? i really need the subentity to be removed!
Thanks!
As requested - I"m pasting my hbm files:
For Entity:
<?xml version="1.0" encoding="utf-8" ?>
- <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Com.Project.Shared.Common" namespace="Com.Project.Shared.Common.Entities">
- <class name="Entity" table="Entities" lazy="false">
- <id name="ID">
<generator class="guid" />
</id>
<property name="Name" />
<property name="Description" />
<property name="EndTime" />
<property name="StartTime" />
<property name="State" />
<property name="Stored" />
<property name="ClassRoomID" />
<property name="Score" />
<many-to-one name="Network" class="Network" column="NetworkID" />
- <bag name="Scenarios" cascade="all">
<key column="EntityID" />
<one-to-many class="EntScenario" />
</bag>
- <bag name="TimeLineEvents" order-by="TimeStamp" cascade="all">
<key column="EntityID" />
<one-to-many class="TimeLineEvent" />
</bag>
- <bag name="SubEntity" table="SubEntities" cascade="all-delete-orphan">
<key column="EntityID" />
<one-to-many class="SubEntity" />
</bag>
</class>
</hibernate-mapping>
for SubEntity:
<?xml version="1.0" encoding="utf-8" ?>
- <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Com.Project.Shared.Common" namespace="Com.Project.Shared.Common.Entities">
- <class name="SubEntity" table="SubEntities" lazy="false">
- <id name="ID">
<generator class="guid" />
</id>
<many-to-one name="Name" class="EntName" column="NameID" />
<many-to-one name="Station" class="EntStation" column="StationID" />
- <bag name="Performances" table="EntPerformances" cascade="all">
<key column="SubEntityID" />
- <composite-element class="Performance">
<property name="Rank" />
<property name="Remark" />
<many-to-one name="Category" class="PerformanceCategory" column="CategoryID" index="ListIndex" />
</composite-element>
</bag>
</class>
</hibernate-mapping>
The tester i use is:
Entity newEntity = _dal.GetAll<Entity>()[0];
ObservableCollection<SubEntity> subEntities = newEntity.ObservableSubEntities;
subEntities .RemoveAt(1);
_dal.SaveItem<Entity>(newEntity);
This just turned the EntityID column in subentity into Null - but doesnt delete it.
I appericiate your help, guys.

Answer 1

The bag needs to have inverse="true" on it if you want it to work as expected.
This tells NHibernate that Entity is responsible to managing the relationship (and you'll be able to make your FK column non-null)