Hello,
I#ve got following problem:
1. I'm loading an persistent object from my MySQL Database. This object contains a set of other objects. (These objects are found by a many-to-many association to another table)
2. During my application I add some more objects to this set.

So far so good

3. Now I want to update the main-object in that way, that the new objects in the set are added to the table, which refers to the n-m-relationship.

Is this possible? For learning hibernate I've used 'A Developer's Botebook' by James Elliot, but there's only a example for saving a new Object, containing a set.


This is the code for the set from the main-object mapping-file:
<set name="feiertage" table="standort_feiertage" inverse="true" >
<key column="stand_id" />
<many-to-many class="de.company.controlling.hibernate.Feiertag" column="f_id" />
</set>

Thanks
FPC

set cascade property in mapping to save-update or all(-delete-orphan)

that is: set the cascade property on the many-to-many to save-update, since all infers delete and this is probably not what you want on a many-to-many.

That means, if I alter my code to this:

<set name="feiertage" table="standort_feiertage" inverse="true" cascade="save-update" >
<key column="stand_id" />
<many-to-many class="de.company.controlling.hibernate.Feiertag" column="f_id" />
</set>


Hibernate will put the IDs of the Feiertag- and the Standort-object into the standort_feiertag-table? That's what I'm aming for.

That it will do if you update the "main object". If you set the cascade property, the newly created "Feiertage"s will be inserted in theit own table as well.

Ok, but I've already tried to update the main-object and hibernate does not throws any exception, but there are no new entries in my 'standort_feiertage'-table...

Normally it should complain if a reffernced collection contains transient objects and the association is not cascading. Maybe you can show the code.

I've got the problem!!!

<set name="feiertage" table="standort_feiertage" inverse="true">

didn't work, but

<set name="feiertage" table="standort_feiertage">

work fine!

it's really usefull to read the reference guide and the wiki about parent/child relationship.
Have you read it?

I've read the Chapter in 'A Developer's Notebook', but I've looked at the wrong example for copying it. The example showed the other side of the n-m-realtionship...

Sry

you'll have to check twice some 'A Developer's Notebook' samples... all is not correct in this book.
It's ok to learn some ideas but check the wiki and reference guide, it has good explanations.
Hibernate in action is actually the best book to understand what is behind all mapping parameters.