[fdo-internals] FDO OGR Provider: NULL values in integer Field

Traian Stanev traian.stanev at autodesk.com
Mon Feb 22 14:19:48 EST 2010


I fixed this bug on September 19, 2009. Here is my svn commit (revision 4928) log:

Correct implementation of FdoIFeatureReader::IsNull().
Previously, the function always returned false and then
attempts to get a null value would return the default value.

Unfortunately, MapGuide uses ancient builds of FDO.


-----Original Message-----
From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-bounces at lists.osgeo.org] On Behalf Of Gabriele Monfardini
Sent: Monday, February 22, 2010 1:43 PM
To: fdo-internals at lists.osgeo.org
Subject: [fdo-internals] FDO OGR Provider: NULL values in integer Field

Hi all,

I'm using FDO 3.4.0 OGR provider to connect to a PostgreSQL db (using
a modified GDAL library built with PostgreSQL support).
In fact, I'm using Mapguide Open Source 2.1 that uses FDO 3.4.0.

I'm trying to stylize a layer in Mapguide, aka doing a query that
involves searching for NULL (and NOT NULL) values in an integer field
of a PostgreSQL table.
After a lot of fiddling it seems that tuples with NULL values can be
retrieved only searching for tuples that have the value 0 in that

This is obviously very odd since 0 is a valid integer, so it appears
that I cannot distinguish tuples with proper zeros in the field from
tuples with unknown values.
Moreover ogr itself is able to support NULL values correctly.

I've read this previous thread

Is FDO OGR provider avoiding NULL value intricacy when dealing with
integer fields converting the NULL value in a zero?

Do you suggest opening a bug against FDO OGR provider or it is a
by-design behaviour of FDO OGR provider?


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