Managing layers from a specific group with PyQGIS

Question

I have some layers loaded in QGIS, in various groups. I want, with PyQGIS, do some stuff on layers from one of theses groups, like adding geometry type to the layer name.
This way, I can do it on all layers :
layers = QgsProject.instance().mapLayers().values()
for layer in layers:
   layer.setName(layer.name()+"_"+QgsWkbTypes.displayString(layer.wkbType()))

This way, I can access layer names from one specific group :
root = QgsProject.instance().layerTreeRoot()
my_group = root.findGroup('My group')
for layer in my_group.children():
   print(layer.name())
   if isinstance(layer, QgsLayerTreeLayer):
      layer.setName(layer.name()+"_"+QgsWkbTypes.displayString(layer.wkbType()))

The "print" of layer name works, but I can't change name, either get the geometry type. I get this error :
AttributeError: 'QgsLayerTreeLayer' object has no attribute 'wkbType'

Does someone know what is the correct way to do that?

Kadir Şahbaz · Accepted Answer

You should add layer() method to layer object. layer is an instance of QgsLayerTreeLayer. It doesn't have wkbType attribute, but  QgsVectorLayer has.
Change layer.wkbType() to layer.layer().wkbType(). layer.layer() returns the map layer associated with layer.
root = QgsProject.instance().layerTreeRoot()
my_group = root.findGroup('My group')
for layer in my_group.children():
   if isinstance(layer, QgsLayerTreeLayer):
      layer.setName(layer.name() + "_" + QgsWkbTypes.displayString(layer.layer().wkbType()))

Vincent Bré · Answer

If each layer of your QGIS project has a unique name, you can use the following code.
The loop retrieves the name of the layers of your group then you will identify the layer with the mapLayersByName method and you will be able to manipulate it easily.
root = QgsProject.instance().layerTreeRoot()
my_group = root.findGroup('My group')

layer_list = [layer.name() for layer in my_group.children()]
for layer in layer_list:
    update_layer = QgsProject.instance().mapLayersByName(layer)
    for lay in update_layer:
        lay.setName(lay.name()+"_" +QgsWkbTypes.displayString(lay.wkbType()))

Managing layers from a specific group with PyQGIS

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