Re: [OJB-developers] Detecting and mapping null Integer values

[Thomas M. <tho...@ho...>]

Hi Darren,

Darren Syzling wrote:

> How can I detect null values for Integer, Long, Double etc Java class attributes
> ?  Let's say we're mapping an object which has the following attributes:
> 
> class Test
> {
>   Integer id;
>   String name;
>   Integer sales;
> }
> 
> 
> Let's assume that both name and sales can be null.  When retrieving this object
> from the database using the PersistenceBroker the String reference will be null
> but the sales reference will in fact refer to an Integer object with a zero
> value.  If zero is within the valid range how can we detect that the value is
> actually null.
> 
> This appears to boil down to: JdbcAccess.getObjectFromColumn.  The code to
> convert a string looks like:
> 
> case Types.VARCHAR:
>   result = rs.getString(columnId);
>   break;
> 
> If the string value is null getString will return a null reference.  But for
> Integer (and other classes) the following is used:
> 
> case Types.INTEGER:
>   result = 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 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 second is 2, ...
      * @return the column value; if the value is SQL <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 created with a zero
> value.
> 
> The Conversion Strategy stuff appears too late in the day to make the
> conversion. 


You are right, things are already on the wrong track at this point....

 How is everybody else handling this or have I missed something ?


cu,

Thomas


> 
> 
> Thanks
> Darren
> 
> 
> 
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