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,

django/contrib/gis/db/models/fields.py

@@ -198,7 +198,7 @@ class GeometryField(Field):
             return geom
 
     def from_db_value(self, value, connection):
-        if value is not None:
+        if value:
             value = Geometry(value)
         return value
 

django/contrib/gis/db/models/sql/compiler.py

@@ -152,7 +152,8 @@ class GeoSQLCompiler(compiler.SQLCompiler):
         for i, alias in enumerate(self.query.extra_select):
             field = self.query.extra_select_fields.get(alias)
             if field:
-                converters[i] = ([], [field.from_db_value], field)
+                backend_converters = self.connection.ops.get_db_converters(field.get_internal_type())
+                converters[i] = (backend_converters, [field.from_db_value], field)
         return converters
 
     #### Routines unique to GeoQuery ####