Two one-to-one relationship

flash.pac · **Joined:** Thu Dec 11, 2003 12:10 pm **Posts:** 16

HI!

How can I make two one-to-one relationship to the same class???

example:

class Application{
Account bankAccount;
Account communityAccount;
}

class Account{
....
}

Tnx!!

sven · **Posted:** Thu Dec 11, 2003 1:14 pm

Just the way you wrote your classes, I'd say.

I think two one-to-one associations in class1 refering to class2 will force you to use foreign keys (in the database model) which refer to the primary key of the table corresponding to class2.

Usually (which means only a single one-to-one association is used) no extra columns are required, while the linked table rows use the same primary key.

Just read the reference for more information on this topic:
http://www.hibernate.org/hib_docs/reference/html/or-mapping.html#or-mapping-s1-9

flash.pac · **Joined:** Thu Dec 11, 2003 12:10 pm **Posts:** 16

My Application's mapping:

Code:

<subclass name="Application">
   <one-to-one name="communityAccount" class="CommunityAccount" constrained="true"/>
   <one-to-one name="bankAccount" class="BankAccount" constrained="true"/>
</subclass>

The relationship in Account's mapping

Code:

<many-to-one name="owner" column="owner_id" class="Application"/>

My Table Accounts in DataBase

Code:

+------------+---------------------+----------+----------+
| account_id | creationDate        | owner_id | amount   |
+------------+---------------------+----------+----------+
|          1 | 2003-12-11 14:11:51 |        1 |   52.7   |
|          2 | 2003-12-11 14:11:51 |        1 |   41.8   |

The application is a singleton stored in my DataBase in the first row(id 1) has two accounts,
when I load this row Hibernate throw an exception: More than one row to unique association!

emmanuel · **Posted:** Fri Dec 12, 2003 6:52 am

Something wrong with your PK column ? or something

flash.pac · **Joined:** Thu Dec 11, 2003 12:10 pm **Posts:** 16

Thank All!!

I was resolve this with bag mapping.

Tnx!