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Saving Associated objects

Sunit Dev
Greenhorn

Joined: Aug 05, 2006
Posts: 1
Hello All,

I have one very basic question to ask.

I have 2 tables

Book [Parent table]
Chapter [Child table]

There is a one-to-many relationship between these 2 tables. 1 book has many chapters. Book objects holds collection of Chapter objects.

I am using Spring and Hibernate in my application. We designed our DAO layer to keep the persistence logic separate from application.

Requirement is that, user will send the books and chapters information 2 one method. This method is in Spring manager class. Now we have to store information in both of these tables, as these objects are associated.

My confusion is how to store these 2 objects in 2 different tables with a single save.

As I am getting information about these 2 objects in Spring layer I can't open Hibernate session there as well as not clear either to pass populated objects to DAO layer, which will open the session and will store these objects one by one.

I know this is a basic problem, please guide me.


Thanks
pascal betz
Ranch Hand

Joined: Jun 19, 2001
Posts: 547
you need to either save the objects "manually" in the same transaction:



or specify an appropriate cascade level on the relationship (see hibernate docu)

pascal
Ghulam Rashid
Ranch Hand

Joined: Jan 14, 2002
Posts: 278
There are variuos ways to accomplish it. One approach is -

Book book = new Book();
book.setBookid(100);
book.setBookname("Hibernate in Action");

Chapter chapterOne = new Chapter();
chapterOne.setChapterid(1001);
chapterOne.setChaptername("Introduction to Hibernate");

Chapter chapterTwo = new Chapter();
chapterOne.setChapterid(1002);
chapterOne.setChaptername("Understanding Persistence");


Set chapterSet = new HashSet();
chapterSet.add(chapterOne);
chapterSet.add(chapterTwo);

book.setChapters(chapterSet);

session.persist(book);
tx.commit();
In chapter.hbm.xml you have define <many-to-one> and book.hbm.xml you have define
<set name="chapters" .....>
..
..
<one-to-many class="Chapter" ../>
</Set>

Similary you have to write POJO.

I hope this will help.
 
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