We are using Hibernate 2.1

Our application receives xml files via web services that it then stores to our backend database using Hibernate. Each xml file translates into 10 - 20 backend database records that must be saved. These database records are all saved using the same Hibernate Session.

An example of the problem we are running into is as follows:

The xml file comes in, and using jaxb, is mapped to pojos. We use these pojos to initialize the hibernate objects that get saved to the database. During this process we save several hibernate objects. One is a "parent" object (parentObj) and several of the others are "child" objects (childObjs) of that parent.

I save the parentObj first and then save each childObj in turn. I assumed the parentOjb's Set of childObjs would reflect what was already saved to the database. What I find is that the parentObj's Set of childObjs is null. In other words the the parentOjb's Set of childObjs do not actually reflect what is in the database. To rectify this problem I had to do a Session.refresh(parentObj). This forced the parentOjbs data to be re-read from the database. After doing this the parentObj's Set of childObjs accurately reflected what was in the database.

Can someone explain why this is happening?

We are using level 1 cache only.

You can force Hibernate to sync with database by close()ing or flush()ing the session. If you don't, session (aka. 1st-level cache) will keep objects around in memory until something forces it to sync up with the db.

I should have been more explicit. We are flushing after each save that we do.

Are you saying that Hibernate is not able to sync updates to the database even when the updates are all done using level 1 cache using the same Session?

Do I need to do a Session.clear() and force the database to be re-read the data to ensure the object accurately reflects what's in the database?

Are you saving the parent, then in a separate set of save commands saving the children by themselves?

Yes, although it is all done in the same Hibernate Session. Should I be doing something differently?

yes.

you should be only doing one save. Build up the parent object with its children inside it before you save.



if you have the cascade options set correctly this one save will save the parent and all the children into the database and the parent will exist in memory with all its children set not requiring an extra update.

Many thanks, that's what I was looking for.