When I try to calculate a new field with:

idx = layer.fieldNameIndex(attributeName)

I receive the following error:

AttributeError: 'QgsVectorLayer' object has no attribute 'fieldNameIndex'

What´s the problem? I'm using QGIS 3.0.1 64x in Windows.


2 Answers 2



Use one of the following methods from the QgsFields class:

  1. indexFromName()

    layer = iface.activeLayer()
    layer_fields = layer.fields()
    field_index = layer_fields.indexFromName("FIELD_NAME")
  2. lookupField():

    layer = iface.activeLayer()
    layer_fields = layer.fields()
    field_index = layer_fields.lookupField("FIELD_NAME")
  3. indexOf()

    layer = iface.activeLayer()
    layer_fields = layer.fields()
    field_index = layer_fields.indexOf("FIELD_NAME")

You need to access it via the fieldNameIndex() method of the QgsVectorDataProvider class:

layer = iface.activeLayer()
idx = layer.dataProvider().fieldNameIndex(attributeName)
  • How do you do that in the Python console? I'm a noob.
    – Novvier
    Apr 18, 2018 at 16:28
  • @MarcoUscuchagua - Click on a layer and type layer = iface.activeLayer(). Then type idx = layer.dataProvider().fieldNameIndex("fieldName"). The self` parameter is mainly used for plugins.
    – Joseph
    Apr 20, 2018 at 9:15
  • The error remains. I think it is a error of QGIS and not of my layer.
    – Novvier
    Apr 20, 2018 at 12:17
  • @MarcoUscuchagua - What error are you receiving? Is it the same error as in your question?
    – Joseph
    Apr 20, 2018 at 12:34
  • 1
    I found the solution!! The problem was in the Quick Attribution plugin, its reinstallation solved the problem. Thanks @Joseph
    – Novvier
    Apr 24, 2018 at 0:42

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