Expanding or collapsing layer groups with PyQGIS 3

Question

PyQGIS 2 has a function to expand/collapse a layers with a subset of styles in the Layers panel as follows:

self.iface.legendInterface().setLayerExpanded(self.segments_layer, False)

I know that in PyQGIS 3 self.iface.legendInterface() has been replaced by gsProject.instance().layerTreeRoot() but making that switch in this case produces an error:

AttributeError: 'QgsLayerTree' object has no attribute 'setLayerExpanded'

What is the appropriate replacement for setLayerExpanded in PyQGIS 3?

score 4 · Accepted Answer · answered May 20 '19 at 14:32

4

You can access it from the QgsLayerTreeNode::setExpanded() function:

root = QgsProject.instance().layerTreeRoot()
layer = QgsProject.instance().mapLayersByName('Layer_Name')[0]
myLayerNode = root.findLayer(layer.id())
myLayerNode.setExpanded(True)

answered May 20 '19 at 14:32

Joseph

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@CNIDog - Most welcome, glad it helped :) – Joseph May 21 '19 at 09:22

score 0 · Answer 2 · answered Aug 23 '22 at 22:07

If you want to clean up a giant list of expanded group layers in the table of contents, here's a few lines of PyQGIS that'll do the trick (i.e. collapse all group layers):

root = QgsProject.instance().layerTreeRoot()
nodes = root.children()
for n in nodes:
    if isinstance(n, QgsLayerTreeGroup):
        if n.isExpanded() == True:
            n.setExpanded(False)
            print(f"Layer group '{n.name()}' now collapsed.")

Expanding or collapsing layer groups with PyQGIS 3

2 Answers2

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