get_object_or_404() and get_list_or_404() swallow AttributeError in queryset filtering

[David Hagen]

Here is the code for get_list_or_404:

def get_list_or_404(klass, *args, **kwargs):
    queryset = _get_queryset(klass)
    try:
        obj_list = list(queryset.filter(*args, **kwargs))
    except AttributeError:
        klass__name = klass.__name__ if isinstance(klass, type) else klass.__class__.__name__
        raise ValueError(
            "First argument to get_list_or_404() must be a Model, Manager, or "
            "QuerySet, not '%s'." % klass__name
        )
    if not obj_list:
        raise Http404('No %s matches the given query.' % queryset.model._meta.object_name)
    return obj_list

The try-catch block is far too broad. Any AttributeError raised during the call to filter is swallowed and converted into an incorrect and confusing error message. This should be changed to either if not hasattr(queryset, 'filter'): raise ... or try: method = queryset.filter; except AttributeError: .... The same thing happens with queryset.get(*args, **kwargs) in get_object_or_404'.

[Yuri Shikanov]

I've opened ​PR

[Carlton Gibson]

Just minor edits on patch needed. (Comments on PR.)

[Tim Graham <timograham@…>]

In eb002e78:

Fixed #29135 -- Prevented get_object/list_or_404() from hiding AttributeError raised by QuerySet filtering.