Hi all,

I am using JDBC transaction management in my JSF application running on tomcat. I am however wondering how to make sure that all queries are committed (which I think is required?).

For example, I have a JSF detail page to show everything of a project. First I do a get of the project:




As you can see, I don't commit here to not detach the object. JSF will call some getters while rendering my page, and hibernate will equally need to get these lazy properties from the database.
So, as you can see my transaction is never committed.
- Is that a problem?
- How can I best solve this? Is there a way to get an object with all lazy properties so that I could get them all at once and commit immediately after?

Thanks,
Steven

Adding to this, I use ThreadLocalSessionContext and so I am wondering where the transaction would actually be destroyed.

Hi,

In this scenario (during retrieve operations), we dont use transactions i.e we never start the transaction. I think transaction is not necessary for retrieve operations.

Otherwise we can start the transaction get all the child record and stored it in a pojo, return it and then commit the transaction.

Regards,
Siva

Are you kidding me?

Read this on sessions and transactions!
http://www.hibernate.org/42.html

It is totally FALSE and BOGUS to state that transactions aren't needed for retrieval.

I guess Christian, Max and the others are tied of fighting such nonsense.

Thanks xantros,

that at least confirms what I was thinking ;) I read in some hibernate article that with the threaded method the transactions are started with beginTransaction() and should be closed at all times since Hibernate cannot know when the JVM will cut off the thread.

Still my question stands. For those who are not familiar with JSF, I have a Java bean where in the constructor I retrieve an object from my DAO. The object is however not fully retrieved because if has several properties defined "lazy".

Then, later on in the execution, JSF calls getObject().getName() . Now if getName() is lazy, the object must not be detached which is why I don't commit.

Just an idea: Should I maybe perform a commit() in the finalise() method of my bean then?

Well, in fact it is NOT a question of commit or not commit - it is a question of keeping the session opened (which you apparently are doing) or closing the session. If you would close the session, you would have a detached object and calling later "getObject().getName()" could result in the famous LazyInstantionException.

So, the whole point in such a scenario is: if you keep the session opened, you must eventually come to a point where you are closing the session. Else your session would grow and grow with persistent objects and you would get a memory problem.

Remember: trransaction.commit and session.close are totally different things.

Carlo

have you looked into open session in view? You can implement it as either a servlet filter or an aspect.


Farzad-

Thanks,
could you please explain a bit what you mean by this?

I can't explain a lot more than this: http://www.hibernate.org/43.html



Farzad-

Great! Thank you.

Still one more thing... when you perform an update and later require the changed data, won't you need to commit in between those two statements?

If so, it is not sure that at the end of the page a session is still open (ie not committed), so what will commit() do then?

You won't have a problem if the two are in the same transaction. Modified data is visible to the same transaction (and possibly to other transactions) and a commit is not needed for that. If transactions are isolated from each other then a commit is needed so that the data modified in transaction T1 is visible to transaction T2, and this is not your case as I understand.



Farzad-

Going to give it a try tomorrow ;)

Thinking about it though, I hope beginTransaction() is a lightweight action since a lot of non-db pages will have this executed too... :s

You should be able to tweak it per command sent to the sever. It's true not every action needs a hibernate session and/or transaction.



Farzad-

Allright, things worked out fine.
In fact it also solved my problems with broken pipes to the mysql database.

Thanks