AW: [OJB-developers] Detecting and mapping null Integer values
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AW: [OJB-developers] Detecting and mapping null Integer values
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From: Mahler T. <tho...@it...> - 2002-02-14 12:23:12
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Hi Jakob,
After having a short look at the code I believe that you are right!
I'll put it on my todo list!
thanks,
Thomas
> -----Urspr=FCngliche Nachricht-----
> Von: Jakob Braeuchi [mailto:jbr...@ho...]
> Gesendet: Donnerstag, 14. Februar 2002 08:50
> An: Thomas Mahler
> Cc: obj...@li...
> Betreff: Re: [OJB-developers] Detecting and mapping null=20
> Integer values
>=20
>=20
> hi thomas,
>=20
> i think the method set() of PersistentField could be =20
> streamlined a lot when
> using f.set(obj,value) instead of the if-else-cascade.
>=20
> public void set(Object obj, Object value) throws=20
> IllegalAccessException,
> IllegalArgumentException
> {
> boolean before =3D getField().isAccessible();
> AccessController.doPrivileged(new SetAccessibleAction());
> Field f =3D getField();
> Class type =3D f.getType();
> try
> {
> f.set(obj,value);
> }
> catch (IllegalArgumentException ex)
> {
> getField().setAccessible(before);
> LoggerFactory.getDefaultLogger().error(ex);
> LoggerFactory.getDefaultLogger().error("field: " +=20
> fieldname + ",
> type: " + type);
> LoggerFactory.getDefaultLogger().error("value: " +=20
> value + ", type:
> " + value.getClass());
> throw ex;
> }
> getField().setAccessible(before);
> }
>=20
> jakob
>=20
> ----- Original Message -----
> From: "Thomas Mahler" <tho...@ho...>
> To: "Darren Syzling" <Dar...@cw...>
> Cc: <obj...@li...>
> Sent: Wednesday, February 13, 2002 8:09 PM
> Subject: Re: [OJB-developers] Detecting and mapping null=20
> Integer values
>=20
>=20
> > Hi Darren,
> >
> > Darren Syzling wrote:
> >
> > > How can I detect null values for Integer, Long, Double=20
> etc Java class
> attributes
> > > ? Let's say we're mapping an object which has the=20
> following attributes:
> > >
> > > class Test
> > > {
> > > Integer id;
> > > String name;
> > > Integer sales;
> > > }
> > >
> > >
> > > Let's assume that both name and sales can be null. When=20
> retrieving this
> object
> > > from the database using the PersistenceBroker the String=20
> reference will
> be null
> > > but the sales reference will in fact refer to an Integer=20
> object with a
> zero
> > > value. If zero is within the valid range how can we=20
> detect that the
> value is
> > > actually null.
> > >
> > > This appears to boil down to:=20
> JdbcAccess.getObjectFromColumn. The code
> to
> > > convert a string looks like:
> > >
> > > case Types.VARCHAR:
> > > result =3D rs.getString(columnId);
> > > break;
> > >
> > > If the string value is null getString will return a null=20
> reference. But
> for
> > > Integer (and other classes) the following is used:
> > >
> > > case Types.INTEGER:
> > > result =3D new Integer(rs.getInt(columnId));
> > > break;
> > >
> >
> >
> >
> > I get your point. But: how should the above code look like to =
handle
> > your problem correctly? I have no idea.
> > If you (or somebody else) tell me how this section should=20
> look like I
> > will change it!
> >
> >
> > java.sql.ResultSet does not tell you that a column is NULL. It just
> > returns a 0. Of course this is wrong. But SUN specified it this =
way.
> > Or am I missing something? From the java.sql.ResultSet Source:
> >
> > /**
> > * Gets the value of the designated column in the current row
> > * of this <code>ResultSet</code> object as
> > * an <code>int</code> in the Java programming language.
> > *
> > * @param columnIndex the first column is 1, the=20
> second is 2, ...
> > * @return the column value; if the value is SQL=20
> <code>NULL</code>,
> > * the value returned is <code>0</code>
> > * @exception SQLException if a database access error occurs
> > */
> > int getInt(int columnIndex) throws SQLException;
> >
> >
> > > getInt will return 0 for null and the an integer will be=20
> created with a
> zero
> > > value.
> > >
> > > The Conversion Strategy stuff appears too late in the day=20
> to make the
> > > conversion.
> >
> >
> > You are right, things are already on the wrong track at=20
> this point....
> >
> > How is everybody else handling this or have I missed something ?
> >
> >
> > cu,
> >
> > Thomas
> >
> >
> > >
> > >
> > > Thanks
> > > Darren
> > >
> > >
> > >
> > >
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