Hibernate 3.1.3

I have only ever used Table-Per-Concrete-Class mapping strategies, but now need to map more complicated stuff.

I have 2 kinds of Accounts: Company-Accounts and Person-Accounts

Company-Accounts are associated with one or more Companies, each of which then are associated with one or more Persons.

Person-Accounts have no Company at all, and are associated directly with one and only one Person.

I have a discriminator in Account thats tells me what type of Account it is.

I think its some combination of Table-Per-Class-Hierarchy and Table-Per-Subclass, or perhaps some usage of implicit polymorphism.

I am using surrogate identity keys throughout. DB is db2 v8 if that matters.

Any help appreciated.

aj

That's plain old table per subclass. You don't even have to make use of the discriminator (though you can if you like). A given account is going to have a row in either the company accounts table, or the person accounts table, but not both. The table per subclass section in the refdocs (9.1.2) fits your description perfectly.

The fact that the company accounts class includes a collection of person accounts is incidental to the polymorphism issue.

If you have trouble mapping this, post again.

Thankyou very much for your help. I'm almost there.

I have
<joined-subclass name="CorporateAccount" table="company">
<key column="account_id"/>
.....
and
<joined-subclass name="PersonAccount" table="person">
<key column="account_id"/>
.....
in my Account.hbm.xml

So this means that I have to create separate CorporateAccount.java & PersonAccount.java classes, as well as CorporateAccount.hbm.xml &
PersonAccount.hbm.xml files?

A particular account can be associated w/ many CorporateAccounts,
but only one PersonAccount. Do I need to map this somehow? Does
the <joined-subclass> above for CorporateAccount need an embedded <set> or something? Is one-to-many inherent in <joined-subclass>?

What does the CorporateAccount.java contain? A Set of Companies?
How about PersonAccount.java? A single Person?

thanks tenwit

You need sepate java files for all classes, yes. You don't need separate .hbm.xml files, the <joined-subclass> mapping is the hbm definition of those classes.


Absolutely you need to map the association as a <set>. If both kinds of account have the relationship, put it in the Account mapping, otherwise put it in the correct subclass. <joined-subclass> is not a relationship, it's a polymorphism operator, so there is no one-to-many, or indeed any-to-any relationship implied. When a class A is "related to" another class B via <joined-subclass>, that means that an object of class A is an object of class B: it's not related to a different object of class B.