Hi all,

I am using jdk1.5 and Hibernate3. I have an object with a java.lang.Boolean value which is mapped as follows:



The value in the database is null, but the value on the object is false, I presume because of autoboxing.

How can I prevent this initialisation. I need to see if the value has been set in the DB, and therefore I need the field to be null.

Any ideas?

Thanks,

Colin

What is your datatype on your Java object, boolean or Boolean?

Ok, it's early, lol.

So Boolean really get initialized to false under 1.5? I find that very strange, which is why I initially assumed your java object was using a boolean.

Yeah, it is kinding of driving me nuts :)

Any idea how to prevent it?

It is because of autoboxing. I am assuming that if the column returns a null that you still want the coresponding object to also be null. In that case you would have to create a custom user type.

It's quite simple. You don't have to update the POJO. But you will have to update the mapping file in this case. Inside the user type class that you create, you will define the behavior that you want.

I had to create these types for Nullable int primative and the like.

Here's an example for boolean:

package com.sobetech.hibernate.type.primative;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;

/**
* com.sobetech.hibernate.type.NullableBoolean
*
* @author John Murray - Sobetech
*
* Creation Date: Aug 24, 2004
*/
public class NullableBoolean implements UserType
{
/* (non-Javadoc)
* @see org.hibernate.usertype.UserType#assemble(java.io.Serializable, java.lang.Object)
*/
public Object assemble(Serializable cached, Object owner) throws HibernateException
{
return cached;
}

/* (non-Javadoc)
* @see org.hibernate.usertype.UserType#disassemble(java.lang.Object)
*/
public Serializable disassemble(Object value) throws HibernateException
{
return (Serializable)value;
}

/* (non-Javadoc)
* @see org.hibernate.usertype.UserType#hashCode(java.lang.Object)
*/
public int hashCode(Object object) throws HibernateException
{
return object.hashCode();
}

/* (non-Javadoc)
* @see org.hibernate.usertype.UserType#replace(java.lang.Object, java.lang.Object, java.lang.Object)
*/
public Object replace(Object original, Object target, Object owner) throws HibernateException
{
return original;
}

/* (non-Javadoc)
* @see org.hibernate.UserType#sqlTypes()
*/
public int[] sqlTypes()
{
int[] typeList =
{Types.BIT};
return typeList;
}

/* (non-Javadoc)
* @see org.hibernate.UserType#returnedClass()
*/
public Class returnedClass()
{
return Boolean.class;
}

/* (non-Javadoc)
* @see org.hibernate.UserType#equals(java.lang.Object, java.lang.Object)
*/
public boolean equals(Object x, Object y) throws HibernateException
{
return Hibernate.BOOLEAN.isEqual(x, y);
}

/* (non-Javadoc)
* @see org.hibernate.UserType#nullSafeGet(java.sql.ResultSet, java.lang.String[], java.lang.Object)
*/
public Object nullSafeGet(ResultSet rs, String[] names, Object owner)
throws HibernateException, SQLException
{
Boolean thisBoolean = (Boolean)Hibernate.BOOLEAN.nullSafeGet(rs, names[0]);
if(thisBoolean == null) return new Boolean(false);
return thisBoolean;
}

/* (non-Javadoc)
* @see org.hibernate.UserType#nullSafeSet(java.sql.PreparedStatement, java.lang.Object, int)
*/
public void nullSafeSet(PreparedStatement ps, Object value, int index)
throws HibernateException, SQLException
{
Hibernate.BOOLEAN.nullSafeSet(ps, value, index);
}

/* (non-Javadoc)
* @see org.hibernate.UserType#deepCopy(java.lang.Object)
*/
public Object deepCopy(Object value) throws HibernateException
{
return value;
}

/* (non-Javadoc)
* @see org.hibernate.UserType#isMutable()
*/
public boolean isMutable()
{
return Hibernate.BOOLEAN.isMutable();
}
}

Are you *sure* of that. I've just tested that on the Annotations project and I don't have any problem retrieving a null object.

Excellent!

I will try it when I get back to work.

Many thanks.

Col

P.S. Seems a bit of an oversight on hibernates part. I would have though a flag on the mapping to turn it off or on would be best :(

I don't experience this behaviour. I have java.lang.Booleans in my classes which can store and retrieve nulls just fine.

Which version are you guys using?

I am using 3.0.5, am trying 3.1 alpha 1.

Tested on Hibernate 3.1 HEAD, but I don't see any reason for a change in this area since a while.

Well I will try with 3.1 HEAD.

Is anybody getting nulls on 3.0.5 (apart from me ;))

Any progress on this guys? It is still happening with jdk 1.5, hibernate 3.05.

yatesco,

I wouldn't wait too long for an update. I would just use the custom type. If and when the change gets made, all you'd have to do is update the hbm.xml of the classes that you used the custom type.

i'm quite sure this is simply not possible - but if you still claim it to be so then produce a SIMPLE & SMALL runnable test case (it should be as simple as having a single boolean mapped)

I tested it, it is not true.