diff options
Diffstat (limited to 'django/db/models/query_utils.py')
| -rw-r--r-- | django/db/models/query_utils.py | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py index 8e804ec3ef..9129d95a0b 100644 --- a/django/db/models/query_utils.py +++ b/django/db/models/query_utils.py @@ -183,11 +183,29 @@ class DeferredAttribute(object): Retrieves and caches the value from the datastore on the first lookup. Returns the cached value. """ + from django.db.models.fields import FieldDoesNotExist + assert instance is not None cls = self.model_ref() data = instance.__dict__ if data.get(self.field_name, self) is self: - data[self.field_name] = cls._base_manager.filter(pk=instance.pk).values_list(self.field_name, flat=True).using(instance._state.db).get() + # self.field_name is the attname of the field, but only() takes the + # actual name, so we need to translate it here. + try: + cls._meta.get_field_by_name(self.field_name) + name = self.field_name + except FieldDoesNotExist: + name = [f.name for f in cls._meta.fields + if f.attname == self.field_name][0] + # We use only() instead of values() here because we want the + # various data coersion methods (to_python(), etc.) to be called + # here. + val = getattr( + cls._base_manager.filter(pk=instance.pk).only(name).using( + instance._state.db).get(), + self.field_name + ) + data[self.field_name] = val return data[self.field_name] def __set__(self, instance, value): |