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Hibernate is returning proxy objects even if no matching row is found on the database

Ovidiu Guse
Greenhorn

Joined: Oct 12, 2008
Posts: 7
Hi guys,

I have an issue with Hibernate and I don't know for sure if it is me doing something wrong or this is a bug / "feature". Maybe someone has stepped into the same problem and there is a way out.

Supposing I have a table 'Persons' with the normal structure: ID, first_name and last_name, and the following records:

ID FIRST_NAME LAST_NAME
1 Jon Doe
2 Jane Doe

On my persistence service implementation (Spring based), I have a method like:

public Person findById(final Serializable id) {
return getHibernateTemplate().load(Person.class, id);
}

Now, everything is working fine if I'm passing to this method one of the valid IDs 1 or 2.

The problem appears when I'm passing for example -1 or 3, which do not exist at the time of the query in the table. The result I'm getting is a proxy object with all fields set to null, when in fact I was expecting the null value as result. And of course, my code implements specific behavior depending on that operation result, for example if the result is null, will throw an exception triggering some other execution paths.

First I guessed it was because of the javassist bytecode provider used by Hibernate, but it turns out the same thing is happening with the cglib provider. This issue has appeared when using Hibernate 3.2 GA, but is still there in Hibernate 3.5.1 Final.
The only (odd) difference between the two Hibernate version is that in Hibernate 3.2 the proxy object returns the invalid id value used for search (e.g. person.getId() returns -1 or 3), while Hibernate 3.5.1 will throw an exception about "No row with given identifier was found ..." when trying to read the object's ID value.

I have searched the Hibernate forums and came across these two links which are not pointing to a valid solution:

http://opensource.atlassian.com/projects/hibernate/browse/EJB-167
http://opensource.atlassian.com/projects/hibernate/browse/HHH-1714

For now the ugly solution was to implement the toString() method on every domain object model and after each search like this to log the result object. This will generate an exception if the proxy result is not mapping a valid database row.

Is there a better way to handle this issue, or has somebody a solution in disabling this "beautiful" Hibernate behavior?

Thanks,
Ovi

Ovidiu Guse
Greenhorn

Joined: Oct 12, 2008
Posts: 7
I did found a smarter but still Hibernate intrusive way of handling it. Please check the code bellow with my original method updated (yes, it is a generic entity loading method, that's why I was trying to load via class object and serializable id instead of searching):




Does someone have a better solution?

Thanks,
Ovi
 
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