I need help in mapping a tree object structure. I'd like to store the tree in the following tables (truncated for simplicity):

Category
id
title
parentId

TreePath
id
ancestorId

So, if I have the following tree:

1
/\
2 4
/
3

The tables would look like:

Category
1 "One" 1
2 "Two" 1
3 "Three" 2
4 "Four" 1

TreePath
2 1
3 1
3 2
4 1

(This is based on the article http://fungus.teststation.com/~jon/tree ... ndling.htm)

In the object model, a Category would have a reference to its parent, but would NOT have references to its ancestors. This object structure and table structure allows for easy movement of nodes within the tree and efficient queries when performing recursive subtree searches.

The question I have, is how to create the mapping. I need to insert/modify rows in the TreePath table without having direct references to ancestors in the object model. It would seem that I would need a way to store a single object within multiple tables (a Category object into the Category and TreePath tables). However, I don't think that Hibernate allows this.

Any ideas on how to make this work without adding native insert SQL statements?

Thanks.

Scott

I couldn't follow your link (404 error).

I have a tree to persist, but I store it all in a single table.
In particular, each entity has a many-to-one relationship called parent.
This seems to be like your "Category" table.

I don't think Hibernate will help you do what you're asking.
It seems that your TreePath table specifies all the ancestors for a given object.
But that could easily have inconsistent values.
For example, what if I was to add the row (4,3) to TreePath.
Would it make 4 a child of 3?
Presumably the table would be inconsistent because (4,2) is not in the table.

I think that Hibernate will help you do things in a particular way (using normal forms).
If you want to do things a different way (by having a non-normal form), Hibernate will just make it harder.
My guess is you need to choose either Hibernate or your mapping scheme.

Sorry!

John.