null values in GML

[Steve Lime]

Mateusz is most likely correct. MapServer extracts attributes and
converts when necessary (not very often). If the asterix 
always represents NULL then we could represent as something else (empty
string?) in the DBF code. What does GDAL/OGR
do with NULLs in its output?

Steve

>>> Mateusz Loskot <mateusz at LOSKOT.NET> 12/6/2006 9:44:29 AM >>>
Bart van den Eijnden (OSGIS) wrote:
> Hi list,
> 
> I have a strange phenomenon.
> 
> A shape attribute table has some null values in it (column type
> Real), for instance:
> 
> OGRFeature(nap_speciaal):856 pnt_pntid (String) = 000A2510 .. 
> hgt_hgtwd (Real) = (null) .. POINT (122880 487860)
> 
> Using Mapserver WFS I get the following GML output:
> 
> <ms:pnt_pntid>000A2510</ms:pnt_pntid> .. 
> <ms:hgt_hgtwd>************************</ms:hgt_hgtwd> ..
> 
> Does anybody have an idea what is causing the sequence of asterisks?

Asterix is used to indicate NULL value in Shapefile attribute.
I'm completely not sure, but I suppose MS WFS driver does not handle
asterix as null but accepts it as a string value and puts into output
GML.

Cheers
-- 
Mateusz Loskot
http://mateusz.loskot.net