PYQGIS rule-based renderer with SVG symbols

Question

I am trying to create a rule-based renderer with different SVG icons for each class. For some reason, I keep getting the error :

Rule' object has no attribute 'QgsSvgMarkerSymbolLayer'

Why do I get this error?

Here's the code :

#create root rule

svgStyle = {}
svgStyle['name'] = 'C:/PROGRA~1/QGIS3~1.16/apps/qgis-ltr/svg/transport/transport_train_station2.svg'
svgStyle['size'] = '7'
symbolLayer = QgsSvgMarkerSymbolLayer.create(svgStyle)
symbol = QgsSymbol.defaultSymbol(gares_toutes.geometryType()) 
symbol.changeSymbolLayer(0, symbolLayer)
renderer = QgsRuleBasedRenderer(symbol)
root = renderer.rootRule()

#rule 1 symbology
symbolvoc1 = root.children()[0].clone()
symbolvoc1.QgsSvgMarkerSymbolLayer(symbolvoc)
symbolvoc1.setSize(25)
#rule 2 symbology
symbolvoc2 = root.children()[0].clone()
symbolvoc2.QgsSvgMarkerSymbolLayer('C:/Users/zcami/Documents/STAGE M1/zooms/icones/centraleblue.svg')
symbolvoc2.setSize(15)
symbolvoc7.xOffset = -0.2
symbolvoc7.yOffset = -1.4

#same thing with 5 other rules...

#filter rules
gare = 'whatever'
symbolvoc1.setFilterExpression("\"Name\" = '{}'".format(gare))
symbolvoc2.setFilterExpression("\"Name\" != '{}' AND \"_vocation\" = 'Gare centrale'".format(gare))

#add rules
root.appendChild(symbolvoc1)
root.appendChild(symbolvoc2)

#apply the renderer
layer.setRenderer(renderer)
symborules = QgsRuleBasedRenderer(root)
layer.renderer().symbol().changeSymbolLayer(0, symborules)
layer.triggerRepaint()

Answer 1

symbolvoc1.QgsSvgMarkerSymbolLayer is not a method. It will always fails and throw your mentioned error

Rule' object has no attribute 'QgsSvgMarkerSymbolLayer'

Not sure how you debug but cut & paste each line to find where is your issue. For this error, replace

symbolvoc1 = root.children()[0].clone()
symbolvoc1.QgsSvgMarkerSymbolLayer(symbolvoc)
symbolvoc1.setSize(25)

by

symbolvoc1 = root.children()[0].clone()
symbolvoc1.symbol().setSize(25)