QGIS not finding all layers?

Question

I'm having an issue with QGIS not identifying all layers correctly.

In my project, I have a group named "Mapas" with the following structure:

Layers inside "Mapas":

localizacao_pl municipal_limits_ibge_pl.shp classificacao_climatica_koppen_pl.shp Groups inside "Mapas":

localizacao with the layers: localizacao_pl Google_Satellite_localizacao Clima with two subgroups: Mapa_clima_direito Mapa_clima_esquerdo Inside the Mapa_clima_direito and Mapa_clima_esquerdo subgroups, there are the following layers:

localizacao_pl municipal_limits_ibge_pl.shp classificacao_climatica_koppen_pl.shp

However, when I map layers, it does not show the correct number of layers:

all_layers = QgsProject.instance().mapLayers().values()
# Print names of all layers
for layer in all_layers:
    print(layer.name())

123_localizacao_pl
123_localizacao_pl
123_localizacao_pl
758_classificacao_climatica_koppen_pl.shp
758_classificacao_climatica_koppen_pl.shp
758_municipal_limits_ibge_pl.shp
758_municipal_limits_ibge_pl.shp
Google_Satellite_localizacao

This issue is causing problems because:

I am creating a script to add layers automatically to the project root, then move them to the appropriate group and remove them from the root. This works until the "Localizacao" group is processed; once it enters the "Clima" group, the script does not delete layers from the root. It is not applying styles to all layers with the same name, only a few. How can I determine the cause of this issue?

Answer 1

The problem was that I was using this code to import layers:

def loadVectorLayer(pathToLayer, nameOfLayer, groupName):
try:
    print('Checking if path to layer exists...')
    if not os.path.exists(pathToLayer):
        raise Exception(f"Layer file not found: {pathToLayer}")
    
    print(f'Loading layer from path: {pathToLayer}...')
    vlayer = QgsVectorLayer(pathToLayer, nameOfLayer)
    if not vlayer.isValid():
        raise Exception("Layer failed to load!")
    
    # Adding layer to map
    QgsProject.instance().addMapLayer(vlayer)
    
    # Search and find the layer to clone
    print("Cloning layer...")
    layer = root.findLayer(vlayer.id())
    if layer is None:
        raise Exception("Layer ID not found!")
    clone = layer.clone()
    
    # Find the group
    print('Looking for group...')
    group = root.findGroup(groupName)
    if group is None:
        raise Exception("Group not found!")
    group.addChildNode(0, clone)
    
    # Remove the original layer
    print("Removing original layer...")
    layer_node = root.findLayer(vlayer.id())
    root.removeChildNode(layer_node)
    
    print(f'Layer {nameOfLayer} loaded successfully.')
except Exception as e:
    print(f"An error occurred: {e}")
    print('')

And it was making a copy but keeping it related to the original (when I manually deleted the original in root the copy loses reference). The solution that I found is to change to this code so I don´t need to delete the original:

def loadVectorLayer(pathToLayer, nameOfLayer, groupName):
try:
    print('Checking if path to layer exists...')
    if not os.path.exists(pathToLayer):
        raise Exception(f"Layer file not found: {pathToLayer}")
    
    print(f'Loading layer from path: {pathToLayer}...')
    vector_layer = QgsVectorLayer(pathToLayer, nameOfLayer)
    if not vector_layer.isValid():
        raise Exception("Layer failed to load!")
    
    # Adding layer to map
    QgsProject.instance().addMapLayer(vector_layer, False)
    
    layer = QgsLayerTreeLayer(vector_layer)
    # Find the group
    print('Looking for group...')
    group = root.findGroup(groupName)
    if group is None:
        raise Exception("Group not found!")
    group.insertChildNode(0, layer)
except Exception as e:
    print(f"An error occurred while loading Vector Layer: {e}")
    print('')

Answer 2

The issue is probably related to the fact that you have duplicate layers.

Not just layer names, but the layer definition - including style/visibility settings etc are duplicated.

eg: 123_localizacao_pl

It has printed it 3 times in the output. It is listed 5 times in the layer listing. However 3 of those layer definitions look similar, whilst the other 2 appear to have unique/different styles.

In other words, 3 different definitions.