I am working with Landusefc
and Class
columns (ref table).
What I want is: Selecting all water from "Class"
and giving a value say '8'
in the "Landusefc"
column for these selected features.
Table looks like
I have tried the following code, it works till the selection part but doesn't seem to change the attribute value using the ChangeAttributeValue
.
from qgis.core import *
import processing
layer=processing.getObject('test1')
query= ' "class" = \'Water\' '
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
layer.setSelectedFeatures([k.id() for k in selection])
#using change Attribute to change the value of the selected feature
layer.startEditing()
for feat in selection:
layer.changeAttributeValue(feat.id(), 5, 8)
layer.commitChanges()
Best Answer
SOLUTION 1:
You have to remove
layer.setSelectedFeatures([k.id() for k in selection])
.Because
selection = layer.getFeatures(QgsFeatureRequest().setFilterExpression(query))
line gives you aQgsFeatureIterator
, that's an iterator. When you use that iterator once, you reach the end of the iterator. Then, if you use it again, you get nothing.In your case, when you use
selection
variable (it's an iterator now) in[k.id() for k in selection]
, you reach the end. If you useselection
infor
loop, since you are at the end of the iterator, you don't have any feature now. If you want to be certain, you can add aprint("Foo")
line tofor
loop.SOLUTION 2:
Change
for feat in selection:
intofor feat in layer.selectedFeatures():
. This solution works only on QGIS 2.x.