Return None for null date/time fields in OGR-supported data sources. Thanks to Ariel Mauricio Nunez Gomez for bug report and initial patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9711 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/gdal/field.py

@@ -127,34 +127,34 @@ class OFTDate(Field):
     @property
     def value(self):
         "Returns a Python `date` object for the OFTDate field."
-        yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
         try:
+            yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
             return date(yy.value, mm.value, dd.value)
-        except ValueError:
+        except (ValueError, OGRException):
             return None
 
 class OFTDateTime(Field):
     @property
     def value(self):
         "Returns a Python `datetime` object for this OFTDateTime field."
-        yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
         # TODO: Adapt timezone information.
         #  See http://lists.maptools.org/pipermail/gdal-dev/2006-February/007990.html
         #  The `tz` variable has values of: 0=unknown, 1=localtime (ambiguous), 
         #  100=GMT, 104=GMT+1, 80=GMT-5, etc.
         try:
+            yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
             return datetime(yy.value, mm.value, dd.value, hh.value, mn.value, ss.value)
-        except ValueError:
+        except (ValueError, OGRException):
             return None
 
 class OFTTime(Field):
     @property
     def value(self):
         "Returns a Python `time` object for this OFTTime field."
-        yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
         try:
+            yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
             return time(hh.value, mn.value, ss.value)
-        except ValueError:
+        except (ValueError, OGRException):
             return None
 
 # List fields are also just subclasses