I'm new to hibernate and trying to navigate some issues. Currently I have multiple tables that contain have a foreign key pointing to the primary key of another table. The primary keys in many cases are auto generated. I'm using MS SQL Server so the database creates the generated key. I'm building the objects up and then performing entityManager.persist on the top level object. When I do this I get a constraint violation stating that null is not allowed for the foreign key value. This foreign key came from the primary key of a parent that was to be auto generated. Do I have to persist each parent, retrieve the key, set it on the child and then move on to the child? What I was hoping is that I would have the ability to build a single object and persist that one time without having to do all this individual database management. If I do have to manage it one at a time how do I retrieve it and rollback if necessary. I tried using nested transactions but it wasn't allowed?

Hibernate should be able to do all you need automatically. You'll need to make sure that cascading, entity relations, etc. are done correctly. The parent/child example in the Hibernate documentation should explain most of it. If you are not using hbm.xml mapping files, you may have to dig around in the rest of the documentation to find the corresponding annotations.