I would like to update one ore more fields of my attribute table on demand (f.e. using a QGIS Action) with one simple click.
For now I have to open attribute table or the layer properties, start field calculator, choose the field I want to update, type or paste my expression and run it for every field I need to update.
I tried to use the model builder but I found no way, to simply update a field within the layer without creating a new layer.
Virtual Fields are not helping me in this way, because the recalculation will be time consuming (complex aggregate expression).