Adding new attribute to QgsFeature object

Question

I have tried reading the docs located here but there is no mention of any method that allows you to add new attributes to the feature only modify existing ones.

Something along the lines of:

QgsFeature.addAttribute(name='Score')

A snippet from my code where I attempted to find a workaround is shown below:

 #create score field by copying fields from origin
 #and append the new score field
 fields = QgsFields(source.fields())
 fields.append(QgsField('Score', QVariant.Int))
 for feature in features:
 #set score for each feature
 score = 12
 #set score attribute
 feature.setFields(fields, initAttributes=False)
 feature['Score'] = score
 #add feature to the output
 sink.addFeature(feature, QgsFeatureSink.FastInsert)

However, when I run the plugin I am making, there is no errors but the output has no attribute named Score.

Note: the score variable is not going to be equal to 12 for each feature I just changed it to be like that for simplicity. It will actually be calculated for each feature based on the features in the source layer.

• bugmenot123: You need to register the new attribute on the layer level, not the feature.

Answer 1

fields = lyr.fields()
# create a field instance
name = 'Score'
new_field = QgsField(name, QVariant.Int)
# open an edit session, it closes automatically after the block is executed
with edit(lyr):
 # add new field to the layer if it does not already exist
 if name not in fields.names(): 
 lyr.addAttribute(new_field)
 lyr.updateFields()
 # get the index of the new field
 idx = fields.indexFromName(name)
 for f in lyr.getFeatures():
 lyr.changeAttributeValue(f.id(), idx, 12) # (feature id, field index, value)