Re-order layers in QGIS table of contents using python

Question

I am using the following code in a script tool to import a set of shapefiles from a folder specified by the user, duplicate two of the layers, style all of them and re-order them in the layers panel.

The last piece of code - the bit that re-orders my layers does not work.

I get the following error:

name 'alayer' is not defined See log for more details

What I don't understand is if I split the code into two separate scripts, load/duplicate/style the layers and then run the re-order layers section separately, the code executes perfectly.

Where am I going wrong?

I'm running QGIS 2.14.8

    ##Select_MasterMap_Folder=folder

    import os,sys
    from qgis.core import*
    from PyQt4.QtCore import*
    from qgis.utils import*
    from qgis.gui import *
    import qgis

    source_dir=(Select_MasterMap_Folder)

    for files in os.listdir(source_dir):

            # load only the shapefiles
            if files.endswith("Area.shp"):
                vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:15],  "ogr")

                # add layer to the registry
                QgsMapLayerRegistry.instance().addMapLayer(vlayer)

            if files.endswith("cLine.shp"):
                vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:15], "ogr")

                # add layer to the registry
                QgsMapLayerRegistry.instance().addMapLayer(vlayer)

            if files.endswith("Point.shp"):
                vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:16], "ogr")

                # add layer to the registry
                QgsMapLayerRegistry.instance().addMapLayer(vlayer)

            if files.endswith("Text.shp"):
                vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:12]+" "+files[12:16], "ogr")

                # add layer to the registry
                QgsMapLayerRegistry.instance().addMapLayer(vlayer)

    canvas = qgis.utils.iface.mapCanvas()
    layers = canvas.layers()

    vl = QgsMapLayerRegistry.instance().mapLayersByName('Topographic Line')[0]
    iface.setActiveLayer(vl)
    iface = qgis.utils.iface; vl = iface.activeLayer(); iface.addVectorLayer(vl.source(), vl.name() + " copy", vl.providerType())

    vl = QgsMapLayerRegistry.instance().mapLayersByName('Topographic Area')[0]
    iface.setActiveLayer(vl)
    iface = qgis.utils.iface; vl = iface.activeLayer(); iface.addVectorLayer(vl.source(), vl.name() + " copy", vl.providerType())

    layer= QgsMapLayerRegistry.instance().mapLayersByName('Topographic Point')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/1TopographicPoint.qml')
    layer= QgsMapLayerRegistry.instance().mapLayersByName('Cartographic Text')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/2CartographicText.qml')
    layer= QgsMapLayerRegistry.instance().mapLayersByName('Topographic Line')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/3TopographicLine.qml')
    layer= QgsMapLayerRegistry.instance().mapLayersByName('Topographic Line copy')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/4TopographicLineCopy.qml')
    layer= QgsMapLayerRegistry.instance().mapLayersByName('Topographic Area')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/5TopographicArea.qml')
    layer= QgsMapLayerRegistry.instance().mapLayersByName('Topographic Area copy')[0]
    iface.setActiveLayer(vl)
    layer.loadNamedStyle('P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/6TopographicAreaCopy.qml')

    qgis.utils.iface.mapCanvas().refresh()

    canvas = qgis.utils.iface.mapCanvas()
    layers = canvas.layers()

    for i in layers:
      if i.name() == "Topographic Area":
        alayer = i
      elif i.name() == "Topographic Area copy":
        blayer = i

    root = QgsProject.instance().layerTreeRoot()

    # Move alayer
    myalayer = root.findLayer(alayer.id())
    myClone = myalayer.clone()
    parent = myalayer.parent()
    parent.insertChildNode(5, myClone)
    parent.removeChildNode(myalayer)

    # Move blayer
    myblayer = root.findLayer(blayer.id())
    myClone = myblayer.clone()
    parent = myblayer.parent()
    parent.insertChildNode(5, myClone)
    parent.removeChildNode(myblayer)

    canvas = qgis.utils.iface.mapCanvas()
    layers = canvas.layers()

    for i in layers:
      if i.name() == "Topographic Line":
        alayer = i
      elif i.name() == "Topographic Line copy":
        blayer = i

    root = QgsProject.instance().layerTreeRoot()

    # Move alayer
    myalayer = root.findLayer(alayer.id())
    myClone = myalayer.clone()
    parent = myalayer.parent()
    parent.insertChildNode(2, myClone)
    parent.removeChildNode(myalayer)

    # Move blayer
    myblayer = root.findLayer(blayer.id())
    myClone = myblayer.clone()
    parent = myblayer.parent()
    parent.insertChildNode(3, myClone)
    parent.removeChildNode(myblayer)

    for i in layers:
      if i.name() == "Cartographic Text":
        alayer = i
      elif i.name() == "Topographic Point":
        blayer = i

    root = QgsProject.instance().layerTreeRoot()

    # Move alayer
    myalayer = root.findLayer(alayer.id())
    myClone = myalayer.clone()
    parent = myalayer.parent()
    parent.insertChildNode(1, myClone)
    parent.removeChildNode(myalayer)

    # Move blayer
    myblayer = root.findLayer(blayer.id())
    myClone = myblayer.clone()
    parent = myblayer.parent()
    parent.insertChildNode(0, myClone)
    parent.removeChildNode(myblayer)

qgis.utils.iface.mapCanvas().refresh()

Answer 1

I've edited your code a bit to contain a couple of functions to call these instead of repeating similar lines of code for each layer. I only tested the functions which loads the style and reorders the layers which seems to work. Assume this code is untested but hopefully this will help avoid the error:

##Select_MasterMap_Folder=folder

import os,sys
from qgis.core import*
from PyQt4.QtCore import*
from qgis.utils import*
from qgis.gui import *
import qgis

source_dir=(Select_MasterMap_Folder)
for files in os.listdir(source_dir):
    # load only the shapefiles
    if files.endswith("Area.shp"):
        vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:15],  "ogr")
        # add layer to the registry
        QgsMapLayerRegistry.instance().addMapLayer(vlayer)
    if files.endswith("cLine.shp"):
        vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:15], "ogr")
        QgsMapLayerRegistry.instance().addMapLayer(vlayer)
    if files.endswith("Point.shp"):
        vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:11]+" "+files[11:16], "ogr")
        QgsMapLayerRegistry.instance().addMapLayer(vlayer)
    if files.endswith("Text.shp"):
        vlayer = QgsVectorLayer(source_dir + "/" + files, files[0:12]+" "+files[12:16], "ogr")
        QgsMapLayerRegistry.instance().addMapLayer(vlayer)

vl = QgsMapLayerRegistry.instance().mapLayersByName('Topographic Line')[0]
iface.setActiveLayer(vl)
iface = qgis.utils.iface; vl = iface.activeLayer(); iface.addVectorLayer(vl.source(), vl.name() + " copy", vl.providerType())

vl = QgsMapLayerRegistry.instance().mapLayersByName('Topographic Area')[0]
iface.setActiveLayer(vl)
iface = qgis.utils.iface; vl = iface.activeLayer(); iface.addVectorLayer(vl.source(), vl.name() + " copy", vl.providerType())

qgis.utils.iface.mapCanvas().refresh()
root = QgsProject.instance().layerTreeRoot()
layers = QgsMapLayerRegistry.instance().mapLayers().values()
style_path = 'P:/Office Admin/GIS/Templates/MasterMap styles for QGIS/Emapsite NEW MasterMap styles/'

def load_style(layer, qml):
    layer.loadNamedStyle(style_path + qml)

def reorder_layers(layer, node):
    myalayer = root.findLayer(layer.id())
    myClone = myalayer.clone()
    parent = myalayer.parent()
    parent.insertChildNode(node, myClone)
    parent.removeChildNode(myalayer)

for i in layers:
  if i.name() == "Topographic Point":
    load_style(i, '1TopographicPoint.qml')
    reorder_layers(i, 0)
  if i.name() == "Cartographic Text":
    load_style(i, '2CartographicText.qml')
    reorder_layers(i, 1)
  if i.name() == "Topographic Line":
    load_style(i, '3TopographicLine.qml')
    reorder_layers(i, 2)
  if i.name() == "Topographic Line copy":
    load_style(i, '4TopographicLineCopy.qml')
    reorder_layers(i, 3)
  if i.name() == "Topographic Area":
    load_style(i, '5TopographicArea.qml')
    reorder_layers(i, 4)
  if i.name() == "Topographic Area copy":
    load_style(i, '6TopographicAreaCopy.qml')
    reorder_layers(i, 5)
  else:
    pass

qgis.utils.iface.mapCanvas().refresh()