[QGIS-Developer] PyQGIS code: setting filter expression for value relation widget

[Andreas Neumann]

Hi Germán,

Thank you so much for these suggestions and code snippets.

I also came across the QgsEditorWidgetSetup - but had no idea how to use
it. The Python cookbook did not mention it. The cookbook is really great -
but for interactive forms, there is not so much information.

I will try it and report back.

Thank you very much Germán,
Andreas


On Sun, 19 Feb 2023 at 00:59, Germán Carrillo via QGIS-Developer <
qgis-developer at lists.osgeo.org> wrote:

> Hi Andreas,
>
>
> you can modify your Value Relation widget's filter expression using the
> QgsEditorWidgetSetup class, in this way:
>
> 1) Get the editor widget setup and get a copy of its config dictionary:
>
>     ews = layer.editorWidgetSetup(3)  # *Let's assume your Value Relation
> widget is set for a field with index 3*
>     new_config = ews.config()  # *We'll use the current config as a basis
> to modify only the filter expression*
>
> 2) Modify the config dict's filter expression:
>
>     new_config['FilterExpression'] = 'your new expression'
>
> 3) Apply changes to your layer:
>
>     new_ews = QgsEditorWidgetSetup('ValueRelation', new_config)
>     layer.setEditorWidgetSetup(3, new_ews)  # *Remember that 3
> corresponds to the field index*
>
> And that's it! You should have now a different set of values in the Value
> Relation widget.
>
>
> Regards,
>
> Germán
>
>
>
> El lun, 13 feb 2023 a las 5:40, Andreas Neumann via QGIS-Developer (<
> qgis-developer at lists.osgeo.org>) escribió:
>
>> Hi,
>>
>> I am looking for a code snippet in PyQGIS: how can I change the filter
>> expression for a value relation widget?
>>
>> Technically, the widget seems to be a QComboBox. I can get access to the
>> combobox, e.g. to get the current value - but how can I access the QGIS
>> related functionality, like changing programmatically settings of the value
>> relation widget , such as the filter expression? I found the
>> QgsValueRelationFieldFormatter object, but it doesn't allow me to change
>> the filter expression. Any idea how I would change the filter expression
>> using Python?
>>
>> Thank you for any hints,
>>
>> Andreas
>> _______________________________________________
>> QGIS-Developer mailing list
>> QGIS-Developer at lists.osgeo.org
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
>>
>
> --
> -----------
>    |\__
> (:>__)(
>    |/
> Soluciones Geoinformáticas Libres
> http://geotux.tuxfamily.org/
> https://twitter.com/GeoTux2 <http://twitter.com/GeoTux2>
>
> <http://gis.stackexchange.com/users/4972/germ%c3%a1n-carrillo>
> _______________________________________________
> QGIS-Developer mailing list
> QGIS-Developer at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
>


-- 

--
Andreas Neumann
QGIS.ORG board member (treasurer)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20230224/df7fbf37/attachment.htm>