Load PostGIS or Oracle Spatial Raster Layer using PyQGIS

How do we load Rasters stored in PostGres-PostGIS or Oracle Spatial 11g into QGIS using PyQgis ?

I am able to load vector layers from Oracle 11g with below code.What changes are necessary to add Raster layers.The files are in tif format.

#Connect to Oracle and Fetch Table Names 
con = cx_Oracle.connect('myoradb/myoradb@189.53.61.140:1521/newdev')
print con.version
cur = con.cursor()
cur.execute(u"select TABLE_NAME from user_tab_columns where data_type='SDO_GEOMETRY'")

tables = cur.fetchall()


uri = QgsDataSourceURI()
uri.setConnection("189.53.61.140", "1521", "newdev", "myoradb", "myoradb")


QgsProject.instance().writeEntry('WFSLayers', "/", [])


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() ]
   pWfsLayer.append(u'%s' % vlayer.id())
   pLayers.append(u'%s' % vlayer.name())
   pLayerIDs.append(vlayer.id())

   render.setLayerSet(lst)
   rect = QgsRectangle(render.fullExtent())            
   rect.scale(1.1)
   render.setExtent(rect)