[QGIS-Developer] Remove layer variable

[Simon Gröchenig]

Thank you, Nyall. That works.

Simon

Am 05.06.2025 01:23, schrieb Nyall Dawson:

> On Mon, 2 Jun 2025 at 19:16, Simon Gröchenig via QGIS-Developer
> <qgis-developer at lists.osgeo.org> wrote:
> 
>> Hi,
>> 
>> how can I remove a layer variable with Python?
>> 
>> The following returns true, but does not work.
>> 
>> QgsExpressionContextUtils.layerScope(layer).removeVariable("variable_name")
> 
> That's cos it's just removing the variable from a copy of the layer's
> expression context scope, not from the layer itself.
> 
> It's rather gross, but try
> https://qgis.org/pyqgis/3.40/core/QgsExpressionContextUtils.html#qgis.core.QgsExpressionContextUtils.setLayerVariables
> -- you'll need to first retrieve the existing variables via
> https://qgis.org/pyqgis/3.40/core/QgsExpressionContextUtils.html#qgis.core.QgsExpressionContextUtils.layerScope
> and then build a dictionary of the variables you want to keep by
> iterating over 
> https://qgis.org/pyqgis/3.40/core/QgsExpressionContextScope.html#qgis.core.QgsExpressionContextScope.variableNames
> 
> Hope that helps!
> Nyall
> 
>> Best regards
>> Simon
>> 
>> _____________________
>> Simon Gröchenig
>> GIS Support und Training
>> Treffling 73 - 9871 Seeboden - Österreich
>> Tel.: +43 699 11 22 31 22
>> Web: https://www.sgroe.at
>> E-Mail: gis at sgroe.at
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-- 
_____________________
Simon Gröchenig
GIS Support und Training
Treffling 73 - 9871 Seeboden - Österreich
Tel.: +43 699 11 22 31 22
Web: https://www.sgroe.at
E-Mail: gis at sgroe.at
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