QGIS » QGIS Application

#!/usr/bin/env python

# -*- coding: utf-8 -*-

# ----- define interface -----

##Virtual Layers (QGIS 2.x)=group

##Create point on surface=name

##Input_layer=vector

##Output_layer=string vl_

##Unique_identifier_column=string gid

##Geometry_column=string geom

from qgis.core import QgsVectorLayer, QgsMapLayerRegistry

otptlyr = Output_layer

uic = Unique_identifier_column

gmc = Geometry_column

inptlyr = processing.getObject(Input_layer)

crs = inptlyr.crs().authid()

crs = crs[5:]

query = """SELECT

        rowid AS '{0}' /*:int*/,

        ST_PointOnSurface(geometry) AS '{1}' /*:point:{2}*/

FROM '{3}';

""".format( uic, gmc, crs, inptlyr.name() )

vlayer = QgsVectorLayer( "?query={}".format(query), otptlyr, "virtual" )

QgsMapLayerRegistry.instance().addMapLayer(vlayer)