how to remove one-to-many child from parent given the child id in HQL

Question

I've got

class Parent
{
    IList<Child> Children;
}

class Child
{
}

When deleting a Child I need to remove all references to it from any Parents that reference it.

How can I do this in NHibernate?

There is no Parent FK on Child, the relationship is stored in a 3rd "link" table

Thanks

Answer 1

To make this happen, there needs to be a relationship of some sort, starting from the Child Entity.

Then you can simply use cascade-delete to its 3d (I'm guessing this is a many-to-many) table.

Answer 2

This is not a parent-child relation. Children have only one parent (the belong to the parent). This is a many-to-many relation between independent entities. This is a important difference.

You can't actually remove the "children" from the "parent" directly in HQL the way it is designed now. This are your options:

• load the "parents" into memory and remove the "child" from the list.
• Add a reference from the "child" back to the "parents". Make the other relation inverse. It should actually automatically remove the item in the link table when you remove a "child", because the link would belong to the "child" then.
• Delete the link using native SQL. This is not nice, but also not too bad because it is trivial standard sql.