[OSGeo-Discuss] methods for programatically adding fields to shapefiles

[David Bianco]

I have experience using Perl and the DBI module to do work like this.  I've
read from dbf files in the past, but have not written to one.  Still, I see
no reason why it would be a hangup.    Let me know if you'd like to go in
that direction.

Dave


On Wed, Oct 29, 2008 at 4:56 PM, Alex Mandel <tech_dev at wildintellect.com>wrote:

> Tyler Erickson wrote:
>
>> I am interested in approaches for adding a populated field to a shapefile
>> (for example, adding a new field named 'source_url' with the value
>> 'http://somewebsite.com').  I would like to do this for several thousand
>> files.
>>
>> At first I thought that I might be able to accomplish it using ogr2org
>> with
>> a sql clause, such as:
>>
>> ogr2ogr -sql "select *, 'http://somewebsite.com' as source_url from
>> infile"
>> outfile.shp infile.shp
>>
>> but that didn't work since ogr2ogr supports a limited set of SQL,
>> described
>> at:
>> http://www.gdal.org/ogr/ogr_sql.html
>>
>> Any ideas on how to accomplish this? (I would prefer suggestions that can
>> be
>> scripted with python.)
>>
>> - Tyler
>>
>
> Open a data connection the dbf with python, add a field to the properties
> of the table and populate the field.
>
> There are several ways to connect to a dbf depending on the OS, you could
> use an ODBC connector, or use some other type of dbf driver.
> I haven't looked closely but there might be a dbf driver in the ogr python
> bindings already.
>
> I think my quick fix was to use python windows tools to wrap the dbf com
> object as a python object I could call, but that was a quick a dirty
> solution on windows.
>
> The other thing I've done is to create a blank shapefile with the exact
> same scheme + one field. Do an ogr2ogr -f "ESRI Shapefile" -a (append) of
> the blank shapefile and your existing one, and now you have a new field.
>
> Alex
>
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