Stale data

vitorsouza · **Posted:** Tue Jan 13, 2004 9:50 am

Hi,

I'm developing a web application using Resin 2.10 and Hibernate 2.1.

There is an administration area where we can create Webpage objects and Area objects. Kind of like this:

Area: idArea, name, startingUrl
Webpage: idWebpage, idArea, url

Thus, an Area can be associated with n Webpages.

Here's the problem: when I edit an Area, change its name and go back to the listing, the system shows the old name. I checked the database and the name has been changed.

If I refresh the page a bunch of times and check on the log I can see that Hibernate issues the following SQL command:

Code:

Hibernate: select area0_.idArea as idArea, area0_.name as name, area0_.startingUrl as startingUrl from area area0_

But still displays stale data. If I keep refreshing the page, eventually it shows the updated data, and I see the following SQL code in the log:

Code:

Hibernate: select webpages0_.idWebPage as idWebPage__, webpages0_.idArea as idArea__, webpages0_.idWebPage as idWebPage0_, webpages0_.url as url0_, webpages0_.idArea as idArea0_ from webPage webpages0_ where webpages0_.idArea=? order by webpages0_.url asc

Does anyone have any ideas to what the problem is or can maybe point me some directions to material (forum archive, hibernate reference) related to this problem?

Thanks in advance,

V

michael · **Posted:** Tue Jan 13, 2004 10:01 am

Probably something related to your session handling. Are you using a new session for every transaction? Are you flushing, closing the session correctly? Transaction management?

vitorsouza · **Posted:** Tue Jan 13, 2004 1:04 pm

gloeglm wrote:

Probably something related to your session handling. Are you using a new session for every transaction? Are you flushing, closing the session correctly? Transaction management?

I use the TheadLocal Session pattern (http://www.hibernate.org/42.html). The code for storing an object is like this:

Code:

Session session = (Session)threadLocal.get();
if (session == null) session = createSession(); // Assigns to threadLocal
else if (! session.isConnected()) session.reconnect();

session.saveOrUpdate(object);
session.connection().commit();
session.flush();
session.disconnect();

And the code to retrieve objects, for instance, all objects of a class, is like this:

Code:

Session session = (Session)threadLocal.get();
if (session == null) session = createSession(); // Assigns to threadLocal
else if (! session.isConnected()) session.reconnect();

Query query = session.createQuery("from " + theClass.getName());
List result = query.list();
session.flush();
session.disconnect();

Anything wrong? Anything missing? Anything redundant?

Thanks again,

emmanuel · **Posted:** Tue Jan 13, 2004 1:30 pm

Since you disconnect session, the 1st level cache is used (and it cannot be unplugged). The appropriate usage of session is to close them once your 'user tx' is done.

vitorsouza · **Posted:** Tue Jan 13, 2004 2:51 pm

emmanuel wrote:

Since you disconnect session, the 1st level cache is used (and it cannot be unplugged). The appropriate usage of session is to close them once your 'user tx' is done.

Thank you. Replacing "disconnect" with "close" worked. For documentation purposes, the new code is now like:

Code:

Session session = (Session)threadLocal.get();
if ((session == null) || (! session.isOpen())) session = createSession();

session.saveOrUpdate(object); 
session.flush(); 
session.connection().commit(); 
session.close();

and:

Code:

Session session = (Session)threadLocal.get();
if ((session == null) || (! session.isOpen())) session = createSession();

Query query = session.createQuery("from " + theClass.getName()); 
List result = query.list(); 
session.flush(); 
session.disconnect();

I will, however, make changes to my PersistenceUtil classes, after I look around in the documentation for best practices of Hibernate use in various kinds of applications (standalone, web, client-server, etc.). Suggestions on where to look are welcome.

Thanks again,

emmanuel · **Posted:** Tue Jan 13, 2004 3:37 pm

The wiki area, the Architecture Forum.