Fixed Oracle GIS failures introduced by e9103402c0; refs #18757.

Thanks Marc Tamlyn for the patch.

django/contrib/gis/db/backends/oracle/operations.py

@@ -142,6 +142,17 @@ class OracleOperations(DatabaseOperations, BaseSpatialOperations):
 
     truncate_params = {'relate': None}
 
+    def get_db_converters(self, internal_type):
+        converters = super(OracleOperations, self).get_db_converters(internal_type)
+        geometry_fields = (
+            'PointField', 'GeometryField', 'LineStringField',
+            'PolygonField', 'MultiPointField', 'MultiLineStringField',
+            'MultiPolygonField', 'GeometryCollectionField', 'GeomField',
+        )
+        if internal_type in geometry_fields:
+            converters.append(self.convert_textfield_value)
+        return converters
+
     def convert_extent(self, clob):
         if clob:
             # Generally, Oracle returns a polygon for the extent -- however,