Can a collection in NHibernate be mapped as read-only?

Question

I have a mapping defined where a parent object has a collection of child objects. In my design, I'd like to be able to delete the child objects without having to remove them from the collection on the parent object and re-saving the parent object. However, when I try this, I get the "deleted object would be re-created on save" error. Is there a way to prevent this such that I could simply delete the child object and not worry about removing it from the parent's collection too? That feels like doing double the work. Ideally I'd like to treat the parent's collection as read-only from NHibernate's perspective.

Answer 1

It'd help if you post your mapping files, but it sounds like you need to add Inverse=true to the collection mapping. This means that the child object is responsible for handling any save or updates, not the parent.

However, in the database it's all modelled the same. The child should have a column for the parent row's ID. NHibernate will create different SQL based on the Inverse property though. I'd like to give more detail, but I'm learning NHibernate myself as well.

Answer 2

I believe the only thing you need to do is just set the collection of child objects in the parent's mapping file to be cascade="none".

Of course that will also prevent saving child objects by assigning them to the parent's collection and updating the parent. If that is OK then you got your solution.