[gdal-dev] Shapefile driver and support for Boolean attributes

[Rahkonen Jukka (MML)]

Hi,

I am testing new Boolean data type in OpenJUMP which is saved as Logical when data are exported into shapefiles. Kosmo GIS supports Logical already and Geotools and gvSIG as well. I said Logical is well defined but that is not totally true. Some implementations seem to use space to mean not initialized (NULL) instead of "?" http://jira.codehaus.org/browse/GEOT-2689, or even consider ? to mean "false" instead of NULL. Needs a more comprehensive literature review.

-Jukka-
________________________________________
Even Rouault wrote:

Selon Jukka Rahkonen <jukka.rahkonen at maanmittauslaitos.fi>:

> Hi,
>
> Is there some special reason why the shapefile driver does not support
> Logical (Boolean) data type for attributes? It seems that the "L" data type
> is there in dBase III format
> https://ulisse.elettra.trieste.it/services/doc/dbase/DBFstruct.htm#C1.4 and
> even well defined Value: "? Y y N n T t F f (? when not initialized)".

Jukka,

This is a good point. It could be added indeed. There's some support from it in
shapelib. I'm wondering how well it is supported by other (non GDAL based)
implementations however. Existing OGR would recognize it as a String(1) as far
as I can see.

Even

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