Creating and populating a visibility preset with pyQGIS

Question

I'm trying to create some layer visibility preset in QGIS 2.18 using its API. But, for some reason, when I try to add layers that are visible in legend interface, it simply doesn't work.

Here is the piece of the code that I'm refering to:

# Creating a preset
root = QgsProject.instance().layerTreeRoot()
clPreset = QgsProject.instance().visibilityPresetCollection()
clPreset.insert('MapaPrincipal', QgsVisibilityPresetCollection.PresetRecord())

# Adding visible layers to created preset
root = QgsProject.instance().layerTreeRoot()

for l in root.findLayers():
    if not l.isVisible():
        iface.legendInterface().setLayerVisible(root.findLayer(l).layer(), True)

clPreset.addVisibleLayersToPreset(root, clPreset.presetState('MapaPrincipal'))

When I check for the visible layers added to the visibility preset, it returns an empty list. What am I doing wrong?

Answer 1

Solved:

# Defining a preset
root = QgsProject.instance().layerTreeRoot()
clPreset = QgsProject.instance().visibilityPresetCollection()

namePreset = 'MapaPrincipal'
prRecord = clPreset.presetState(namePreset)

# Adding visible layers to preset
for l in root.findLayers():
    if not l.isVisible():
        l.setVisible(True)

clPreset.addVisibleLayersToPreset(root, prRecord)

# Creating or updating the preset
if clPreset.hasPreset(namePreset):
    clPreset.update(namePreset, prRecord)
else:
    clPreset.insert(namePreset, prRecord)