PyQgis update layers of canvas freezes application

Question

I'm trying to update layer of a QgsProject instance with a timer in a new thread and show the updated data in a QMainWindow. But however I change the attributes/features/layers, it always freezes the application. I understand that the QgisProject lives in the main thread, so is it even possible to change a layer without freezing the application? If yes how?

The code below is what im trying to do in an extra thread.

self.project = QgsProject.instance()
layer = self.project.mapLayersByName(layerName)[0]
        
keyColIdx = layer.fields().indexOf(keyCol)

with edit(layer):
   for feat in layer.getFeatures():
      for colToEdit in colsToEdit:
         colToEditIdx = layer.fields().indexOf(colToEdit)
         try:
            # get item from dataframe
            value = newDf[newDf[keyCol] == str(feat.attributes()[keyColIdx])][colToEdit].item()
            # change attribute
            layer.changeAttributeValue(feat.id(), colToEditIdx, value)
         except:
            pass
canvas.refresh()

score 0 · Answer 1 · answered Dec 14 '21 at 16:51

0

Turns out it does not freeze when you use the changeAttributeValues method of the dataProvider, which has a slightly different syntax though.

answered Dec 14 '21 at 16:51

Bumbibanane

3
3

PyQgis update layers of canvas freezes application

1 Answers1