Hello.

I have following tables:

----------------
T_LOCATION
location_id
street_address
city
country
----------------
T_PERSON
name
location_id
----------------
T_COMPANY
name
location_id
----------------

The idea is to just extract all location specific information into separate table. Every row in the location table used only once - either single Person or single Company points to it.

Using <many-to-one> for Location in the Person class works, but when new location is set for the Person or Company, it is not automatically saved (I have to call session.save(location) before session.save(person)). Is it possible to make save() operation cascade in this scenario? Also I need to delete record from T_LOCATION when Person's location is replaced with totally new. Actually, I need behavior much like collection with cascade="all-delete-orphan" but I do not want to use collection because it is known, there can be only one location for Company, not a set of locations.

Or are there other ways to implement what I want? Eliminating T_LOCATION table, putting all the properties into T_PERSON/T_COMPANY and using <component> is definitely not the best idea because:
1. There actually more than two entities which use location.
2. Some entities has two references to the location table (home_location_id and office_location_id for instance)
2. There are much more fields in the T_LOCATION table than I put in this sample.

Thanks in advance.

You can use all the cascade styles except "all-delete-orphan" on a <many-to-one>. However, there are usually extreme conceptual problems with cascade delete for a <many-to-one> (nothing to do with Hibernate).

Ok, I can not use all-delete-orphan. But what about cascade="all" ? Even if I set

cascade="all"
not-null="true"

for the "<many-to-one>" mapping from Person to Location and new Location to a Person and use session.save(person), I got non-null constraint violation (because Location is not saved before Person). What can I do?

Oh, sorry, of course it is not about "non-null" constraing but about "foreign key does not exist" because when Person is added there is no location with specified location_id yet.

You are mistaken. If you use cascade="save-update" or cascade="all", you should not see a FK violation.

Heh. I have resolved the problem...
It was caused by absence of unsaved-value attribute for <id> elements - I was using primitive types (long instead of Long).

Strange enough...
Hibernate was retrieving nextval from LOCATION sequence before attempting to insert PERSON and that means it was going to save LOCATION anyway. But for some reasons it was planned after the insertion of PERSON. After unsaved-value attribute was added to both entities, everything works fine.

A "long" is a "Long" and not primitive.

I mean I vas using

long id;

instead of

java.lang.Long id;

"long" IS primitive and can not be null :)