fields.py/prep_localized_datetime(): Fix scoping issue.

timezones/fields.py

@@ -110,47 +110,55 @@ def get_db_prep_lookup(self, lookup_type, value):
 def prep_localized_datetime(sender, **kwargs):
     for field in sender._meta.fields:
         if not isinstance(field, LocalizedDateTimeField) or field.timezone is None:
+            field = None
             continue
-        dt_field_name = "_datetimezone_%s" % field.attname
-        def get_dtz_field(instance):
-            return getattr(instance, dt_field_name)
-        def set_dtz_field(instance, dt):
-            if dt.tzinfo is None:
-                dt = default_tz.localize(dt)
-            time_zone = field.timezone
-            if isinstance(field.timezone, basestring):
-                tz_name = instance._default_manager.filter(
-                    pk=model_instance._get_pk_val()
-                ).values_list(field.timezone)[0][0]
-                try:
-                    time_zone = pytz.timezone(tz_name)
-                except:
-                    time_zone = default_tz
-                if time_zone is None:
-                    # lookup failed
-                    time_zone = default_tz
-                    #raise pytz.UnknownTimeZoneError(
-                    #    "Time zone %r from relation %r was not found"
-                    #    % (tz_name, field.timezone)
-                    #)
-            elif callable(time_zone):
-                tz_name = time_zone()
-                if isinstance(tz_name, basestring):
+
+        # Beware python scoping and for loops (for loops don't introduce new scope)
+        # http://stackoverflow.com/questions/233673/lexical-closures-in-python
+        def gen_getset_dtz_field(field):
+            dt_field_name = "_datetimezone_%s" % field.attname
+
+            def get_dtz_field(instance):
+                return getattr(instance, dt_field_name)
+
+            def set_dtz_field(instance, dt):
+                if dt.tzinfo is None:
+                    dt = default_tz.localize(dt)
+                time_zone = field.timezone
+                if isinstance(field.timezone, basestring):
+                    tz_name = instance._default_manager.filter(
+                        pk=model_instance._get_pk_val()
+                        ).values_list(field.timezone)[0][0]
                     try:
                         time_zone = pytz.timezone(tz_name)
                     except:
                         time_zone = default_tz
-                else:
-                    time_zone = tz_name
-                if time_zone is None:
-                    # lookup failed
-                    time_zone = default_tz
-                    #raise pytz.UnknownTimeZoneError(
-                    #    "Time zone %r from callable %r was not found"
-                    #    % (tz_name, field.timezone)
-                    #)
-            setattr(instance, dt_field_name, dt.astimezone(time_zone))
-        setattr(sender, field.attname, property(get_dtz_field, set_dtz_field))
+                    if time_zone is None:
+                        # lookup failed
+                        time_zone = default_tz
+                        #raise pytz.UnknownTimeZoneError(
+                        #    "Time zone %r from relation %r was not found"
+                        #    % (tz_name, field.timezone)
+                        #)
+                elif callable(time_zone):
+                    tz_name = time_zone()
+                    if isinstance(tz_name, basestring):
+                        try:
+                            time_zone = pytz.timezone(tz_name)
+                        except:
+                            time_zone = default_tz
+                    else:
+                        time_zone = tz_name
+                    if time_zone is None:
+                        # lookup failed
+                        time_zone = default_tz
+                        #raise pytz.UnknownTimeZoneError(
+                        #    "Time zone %r from callable %r was not found"
+                        #    % (tz_name, field.timezone)
+                        #)
+                setattr(instance, dt_field_name, dt.astimezone(time_zone))
+            return (get_dtz_field, set_dtz_field)
+        setattr(sender, field.attname, property(*gen_getset_dtz_field(field)))
 
 ## RED_FLAG: need to add a check at manage.py validation time that
 ##           time_zone value is a valid query keyword (if it is one)