POST QUESTIONS ON THE FORUM! COMMENTS HERE SHOULD ADD VALUE TO THE
PAGE!On 27 Sep 2005 19:21, phersh wrote:

>Hi,

>The nullSafeGet doesn't protect from nulls because

>String value = resultSet.getString(names[0]); can return null.

>I've changed nullSafeGet to:
>    public Object nullSafeGet(ResultSet resultSet, String[] names,
>Object owner)
>            throws HibernateException, SQLException {
>        if (resultSet.wasNull()) return null;
>        String value = resultSet.getString(names[0]);
>        if (value == null) return null;
>        return getObject(value);
>    }

I ran into a very subtle bug with this method.  Depending on the
ordering of the property definitions in my class mapping the call to
wasNull() would cause a SQLException.  I changed the method like this:

    public Object nullSafeGet(ResultSet resultSet, String[] names,
Object owner) throws HibernateException, SQLException {
        String value = resultSet.getString(names[0]);
        if (resultSet.wasNull())
            return null;
        return getObject(value);

Maybe this isn't so good if the column type is not 'string' compatible,
but it seems that is the only possibility for this class.

Here's the mapping that failed:
...
<class name="org.egcrc.cfr.hibernate.EnumTestClass" table="ENUM_TEST"
lazy="true">

  <id name="id" column="ID" type="long" unsaved-value="null">
    <generator class="native"/>
  </id>
  <property name="alone" type="org.egcrc.cfr.hibernate.EnumUserType"
column="ALONE"/>
  <property name="foo" type="string" column="FOO"/>
  <property name="internal" type="org.egcrc.cfr.hibernate.EnumUserType"
column="INTERNAL"/>
</class>
...
The class has three instance variables, two of which are Java 1.5 enums,
and one is string.
But if I change this mapping to put the foo property either before the
two enums or after them it works with the original code.  If you look at
the javadoc for ResultSet#wasNull() it states that you must have called
a column getter before calling it.  Perhaps that was not done?  I didn't
have the time to trace through the code in that much detail, but my
change did fix the problem.

I hope this helps someone avoid this problem.