flush() does not commit to database

mark1979 · **Joined:** Sat Sep 27, 2008 6:24 am **Posts:** 3

Hi to all,

I'm using hibernate 3.2, jdk5, & mysql5, I'm following the samples in "Hibernate quickly".

when I use flush() to save a record it doesn't commit in the database(MySql)?

Code:

    Student student = new Student():
    // set student parameters
    session.save(student);
    session.flush(); // does not commit to DB???
    session.close();    

but it works if I use transaction.commit()

Code:

    Student student = new Student();
    // set student parameters
    session.save(student);
    transaction.commit();   

Why does flush doesn't work for me, do I have to configure something in hibernate? am I doing something wrong?

Thank you very much

gonzao_diaz · **Joined:** Mon Nov 26, 2007 2:29 pm **Posts:** 443

Because the code above is not wrapped into a transaction.

Where is the context in which that code runs? If it uses annotations or declarative transactions, make sure that the method calling the 1st code is declared as transactional.

If it is just a sample, client code, manually write code to wrap in into a transaction. As a general rule, everything needs a transaction.

mark1979 · **Joined:** Sat Sep 27, 2008 6:24 am **Posts:** 3

How do I declare the method as transactional? (sorry for dumb question)

I didn't use any annotations for the method. Do you mean by "wrapping it in a transaction", is that I should always create a transaction and use the transaction.commit().

Thanks again.

gonzao_diaz · **Joined:** Mon Nov 26, 2007 2:29 pm **Posts:** 443

You can create a transaction around your code, either programatically (by manually writing transaction code) of declaratively.

Programatically, it means that you create a transaction with code( begin, commit, etc ) on each database interaction.

Code:

Transaction trx=session. ...
trx.begin....

[your persistence code here]

trx.commit();
}catch(...
trx.rollback()

"Declaratively", means that you are using some sort of "managed environment" (such as Spring) that takes care, mainly through configuration external to the code itself, of creating transactions where necessary.

(BTW, if you want the simplest example on how to integrate Hibernate with Spring, go here:
http://hibernar.org/articulos_en/spring ... xample.php
)

Annotations are one of the tools used by managed environments such as Spring to declaratively create transactions as needed. It is the most modern and easy strategy (shown in my article).

Previous declarative strategies to produce transactions made a more low-leve use of AOP (aspect oriented programming) or "Transaction Proxies" declared in your application context wrapping your business objects.

I don't know what the nature of your application is.

If it is a small, trivial application, you can write the transaction code programmatically (by hand).
If it is a web application, use Spring for creatig transactions declaratively, and remove most (or all) the explicit transaction code from your Hibernate logic.

mark1979 · **Joined:** Sat Sep 27, 2008 6:24 am **Posts:** 3

Thanks a lot Gonzalo.