Hi!, I have a simple class with the following xml,
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="credito.Agencia" table="T_Credito">
<id name="codigo" column="P_Codigo" type="long">
<generator class="assigned"/>
</id>
<property name="descripcion" column="A_Descripcion" type="string"/>
</class>
</hibernate-mapping>

I want to save-update this objects in the DB with the saveOrUpdate() method.
I know that I should use (for example) Interceptors because the generator class is "assigned",
but this strategy don't work for my scenario. For example, I wanto to do this:

....
Agencia a = new Agencia();
a.setCodigo(1234);
a.setDescripcion("Test");
session.saveOrUpdate(a); //Here, the insert works fine and Object 'a' is inserted in DB.

then in another execution,

....
Agencia a1 = new Agencia();
a1.setCodigo(1234); //Obs: is the same id.
a1.setDescripcion("Test modif");
session.saveOrUpdate(a1); //I hope that Hibernate try to update 'a1' since the primary key already exists in the DB.

in this point Hibernate throws an Exception of "Violation of PK constraint".

How can I do to resolve this problem?
Thanks.

[b]Hibernate version:[/b]
2.1.8
[b]Mapping documents:[/b]

[b]Code between sessionFactory.openSession() and session.close():[/b]

[b]Full stack trace of any exception that occurs:[/b]

[b]Name and version of the database you are using:[/b]

[b]The generated SQL (show_sql=true):[/b]

[b]Debug level Hibernate log excerpt:[/b]

You have to give Hibernate a way to determine the unsaved state, either don't use assigned, use an interceptor or use unsaved-value on timestamp/version

[quote="michael"]You have to give Hibernate a way to determine the unsaved state[/quote]

This is my problem!, because when I want to persist an object in the DB, I don't know if my object is transient or not (since this object is created before persist it). I could execute a query to verify if the 'id' already exists in the DB and do an update or insert when it don't exists but I want to Hibernate do this for me. On the other hand, I need the id's assigned therefore I can't use other type of generator class.

select-before-update="true"

Actually select-before-update does not help in HB 2.1

You must implement Interceptor.isUnsaved().

HB3 always does the right thing "automatically".

> You must implement Interceptor.isUnsaved().
But...how implement isUnsaved() if I don't know when the object is transient or persistent? since I create objects all the time and try to persist it. For example let us suppose that exists a record in the DB with PK = 1234, then I create an object b:
...
Agencia b = new Agencia();
b.setCodigo(1234);
b.setDescripcion("Test modif");
session.saveOrUpdate(b); //In this point I don't know if already exists a persist object with PK = 1234. In this particular case the objects exists so I hope that Hibernate update the record otherwise I hope that Hibernate 'insert' the object in the DB.

finally, I resolved the problem, simply I implemented the Michael's suggestion: use select-before-update = true. Then all works fine. The final xml is:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="credito.AgenciaCredito" table="T_CreditoAgencia" select-before-update="true">
<id name="codigo" column="P_Codigo" type="long">
<generator class="assigned"/>
</id>
<property name="descripcion" column="A_Descripcion" type="string"/>
</class>
</hibernate-mapping>

Thanks.

I don't understand how this can work. How does Hibernate know to generate INSERT instead of UPDATE for the first object? Could someone explain? thanks

Dmitry

There is very good explanation to this in
http://www.hibernate.org/hib_docs/reference/en/html_single/#manipulatingdata-updating-detached

srigold

srigold, look carefully at Jean's code and comments. He is not updating a detached object, he is persisting a transient: a new object with an assigned key is being persisted using saveOrUpdate(). As far as I understand Hibernate, this shouldn't have worked. Yet the comments say that it did.