Changing attribute values of selected features using PyQGIS

Question

I am selecting the features by "Property_T" and its attribute is 'Open Land' and I want to add some attribute to "SS" field for same record. What is wrong?

from PyQt5.QtCore import QVariant
fn = "D:\Practice\Parcels.shp"
layer = iface.addVectorLayer(fn, '', 'ogr')
caps = layer.dataProvider().capabilities()
if caps & QgsVectorDataProvider.AddAttributes:
    res = layer.dataProvider().addAttributes([QgsField('SS', QVariant.String)])
    layer.updateFields()
query = "Property_T = 'Open Land'"
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.selectByIds([s.id() for s in selection])
iface.mapCanvas().setSelectionColor(QColor('Blue'))
features = layer.selectedFeatures()
for feat in features:
    if feat['Property_T'] == 'Open Land':
        with edit(layer):
            feat['SS'] = 'RR'
            layer.updateFeature(feat)

What are you trying to do and what is the problem with the code you are showing? If Property is Open Land SS field should be set to RR? Edit the question to clearify — BERA, Nov 03 '22 at 05:54
This is an instance of a "wall of code" post. They are treated harshly because they are perceived to state "I don't have the time to write a problem statement, just debug my code without me" — Vince, Nov 03 '22 at 05:57
sir iam selecting the features from parcel and field is Property type and its attribute is "open land" and i want to add the some attribute to SS field for same record — Srikanth Talla, Nov 03 '22 at 06:12

Taras · Answer 1 · 2023-01-06T09:45:52.933

Another option is to work with the selectedFeatureIds() and changeAttributeValue() methods of the QgsVectorLayer class.

ss_idx = layer.fields().lookupField('SS') #index of the "SS" field
with edit(layer):
    for feat_id in layer.selectedFeatureIds():
        layer.changeAttributeValue(feat_id, ss_idx, 'RR')

References:

Changing attribute values of selected features using PyQGIS

1 Answers1