Loading Oracle Spatial Layers in standalone python qgis

Question

I used below script to connect to postgres and load layers successfully.I want to aceive this using Oracle Spatial for both vector and raster loading.How can I achieve that?In other words what is the equivalent of postgis_utils for Oracle Spatial.From QGIS Desktop,I am able to load both raster and vector.This indicates QGIS has certain libraries to connect to Oracle and import GIS data.How can I use those libraries in standalone python script?

uri = QgsDataSourceURI()
uri.setConnection("localhost", "5432", "mydb", "postgres", "passcode")


db = postgis_utils.GeoDB(host="localhost", port=5432, dbname="v",user="postgres", passwd="passcode")
print db
tables =db.list_geotables()
print tables

render = QgsMapRenderer()

for t in tables :
   uri.setDataSource(str(t[1]),  str(t[0]), str(t[6]))
   uri.uri()
   vlayer = QgsVectorLayer(uri.uri(), str(t[0]), "postgres")
   QgsMapLayerRegistry.instance().addMapLayer(vlayer)
   lst = [ vlayer.id() ]
   render.setLayerSet(lst)
   rect = QgsRectangle(render.fullExtent())            
   rect.scale(1.1)
   render.setExtent(rect)

Answer 1

Figured it out by myself.I have used cx_Oracle library to accomplish this:

# Import system modules
from xml.dom.minidom import Document
import string
import os
import sys
from qgis.core import *
from qgis.gui import *
from PyQt4.QtCore import *
from PyQt4.QtGui import QApplication
from PyQt4.QtXml import *
from ctypes import*
import cx_Oracle

strProjetName = "C:/OSGeo4W/apache/htdocs/QGIS-Web-Client-master/projects/myworld.qgs"

if os.path.isfile(strProjetName):
   os.remove(strProjetName)

def add_LayersFromDB():
    QGISAPP = QgsApplication(sys.argv, True)     
    QgsApplication.setPrefixPath(r"C:\OSGeo4W\apps\qgis", True)
    QgsApplication.initQgis()

    #Connect to Oracle and Fetch Table Names 
    con = cx_Oracle.connect('testinstance/[email protected]:1521/new')
    print con.version
    cur = con.cursor()
    cur.execute(u"select TABLE_NAME from user_tab_columns where data_type='SDO_GEOMETRY'")

    tables = cur.fetchall()

    QgsProject.instance().setFileName(strProjetName)
    print QgsProject.instance().fileName()
    render = QgsMapRenderer()

    uri = QgsDataSourceURI()
    uri.setConnection("189.60.67.146", "1521", "new", "testinstance", "testinstance")

    render = QgsMapRenderer()

    for t in tables :
       print str(t[0])

       uri.setDataSource('',  str(t[0]), "GEOMETRY")
       uri.uri()
       vlayer = QgsVectorLayer(uri.uri(),str(t[0]), 'oracle')
       QgsMapLayerRegistry.instance().addMapLayer(vlayer)
       lst = [ vlayer.id() ]
       render.setLayerSet(lst)
       rect = QgsRectangle(render.fullExtent())            
       rect.scale(1.1)
       render.setExtent(rect)

    QgsProject.instance().write()

    cur.close()
    con.close()

    QgsApplication.exitQgis()


add_LayersFromDB()