[Qgis-user] Filtering NULL values from WFS

[Reetz, Michael (NLPVW)]

Dear Chris and Björn,

yes, I have tried end_date is null first. No records are found with this although most record have NULL as end_date.

Cheers,
Michael

Von: chris hermansen <clhermansen at gmail.com>
Gesendet: Dienstag, 26. August 2025 17:45
An: Reetz, Michael (NLPVW) <Michael.Reetz at nlpvw.niedersachsen.de>
Cc: qgis-user <qgis-user at lists.osgeo.org>
Betreff: Re: [Qgis-user] Filtering NULL values from WFS


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On Tue, Aug 26, 2025, 07:54 Reetz, Michael (NLPVW) via QGIS-User <qgis-user at lists.osgeo.org<mailto:qgis-user at lists.osgeo.org>> wrote:
Hello group,

I’ve added a WFS-layer to a project try to define filters on different attributes. It seems not to be possible to filter for NULL values.

Example:

  *   1932 records in total
  *   376 records with a value in a date attribute
  *   20 records with 2005-12-31 as value

If I set the filter to "end_date" = '2005-12-31' the result is 20 records.
If I set the filter to "end_date" != '2005-12-31' the result is 356 records. So only records that have an end date are recognized. Record with NULL as end date are ignored.

Filtering in the attribute table with “is_empty_or_null” works but only for selection.

Is this “normal” behaviour with WFS layers or is there a way to define a filter string that work for all records?

Have you tried

end_date IS NULL

Generally speaking (I'm not sure about this specific case) null is neither equal nor unequal hence the need for a different logical operator, IS.

Can you combine conditions for example

end_date IS NULL or end_date = '2005-12-31'

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