[patch] list_detail and archive_* generic views should default allow_empty to True

[django@…]

Ideally default behaviour should correlate with the assumptions of the majority. Although it is clearly documented otherwise, I suspect that most people (like me :) will assume that the list_detail generic view handles an empty list exactly as it handles a populated list. I was surprised at getting 404s after reseting my database. Current bahviour has the potential to facilitate unnoticed bugs. I suggest defaulting 'allow_empty' to True. Of course this must be weighed against the hassle of backwards incompatibility and I suspect it may lose out on these grounds, but I thought it was worth ticketing for consideration.

[L.Plant.98@…]

I agree. I've already come across lots of scenarios where I have got it wrong and could easily get in wrong in the future and not notice. If you've already populated one item or more in the table you don't notice the behaviour with no items. When you later add searching facilities to the list, and someone enters a search with no results, they suddenly get a 404 error. The current behaviour is unintuitive, and is simply a shortcut for a common pattern that some apps might have, but as such it shouldn't be the default.

[django@…]

I'm glad this came back up. I can see this "feature" catching out newbies (and some oldbies) again and again. As the fix is backwards incompatible it should really be done before 1.0 -> Priority nudge.

[Antti Kaihola]

It would help most newbies if at least the examples in ​the documentation used allow_empty=True for now.

[real.human@…]

yep, i just spent many hours over two days trying to figure out why code that was previously working was now returning a "404" with no useful debug information, either. +1 for this change :)

[anjocee # gmail.com]

I agree, too.

It spent my two or three hours to find out why 404.
and lucky found the answer with google.

btw, I like djanjo very much.

[Jared Kuolt]

I do NOT think this is a defect. It makes sense to me that when an object is not found, it throws a 404 (object not found).

[Gary Wilson <gary.wilson@…>]

Correcting probable spam.

And I also agree that the default should be allow_empty=True.

[Gary Wilson <gary.wilson@…>]

patch coming...

[Gary Wilson <gary.wilson@…>]

default value of allow_empty changed to True for the generic views (archive_* except archive_week which already defaulted to True and object_list) with the documentation changes as well.

[Indy]

+1 from me. The current behaviour is a gotcha.

[(none)]

Milestone Version 1.0 deleted

[Gary Wilson <gary.wilson@…>]

From comments above, I would say this is accepted.

[Malcolm Tredinnick]

I'm not convinced this is "ready for checkin", since it breaks backwards compatibility. Four or five commenters in a ticket does not make a vast majority. At a minimum, I think this should wait until post-0.96 and be part of the backwards compatible changes for 1.0 if we include it.

I'm probably +1 on including the patch, but I know there is code out there relying on the current behaviour (I've written more than a few lines of such code) and breaking existing sites is not cool. So I'm moving this back to "design decision needed" in order to at least hold it over until the forthcoming release prior to the 1.0 push. Then we can decide (along with a bunch of other small items) whether we want to break backwards-compat.

[Jeff Forcier]

I strongly agree that the default ought to be allow_empty=True, so make that five or six commenters ;)

I won't bother reiterating the arguments already made, but I will point out that if possible it'd be nice if this particular default setting was highlighted more strongly in the documentation or an FAQ. It's definitely a FAQ in the literal sense, as in I see it asked all the time.

[Chris Beaven]

I'm +1 too.

[cmgreen@…]

I just got bit by this issue. If it helps, generic views allows_empty brought me to this page wishing that this change is made. I troubleshot almost everything else about my config before I tracked this down.

[Malcolm Tredinnick]

Will everybody please stop posting "me too" comments; it's adds no value to the ticket report, since a few extra comments in a userbase of many thousands does not change the weighting. As mentioned above, this is one of the backwards incompatibility changes we will have after 0.96 is released in preparation for 1.0. Not before 0.96.

[Malcolm Tredinnick]

Err ... replace "backwards compatibility changes" with "backwards compatbility conversations" in the above. :(

[vinay_sajip@…]

Backward compatibility can easily be maintained as follows: change the default value of allow_empty in the view definitions to a setting e.g. DEFAULT_ALLOW_EMPTY. This can be set to False by default in settings.py, and people who want to can change the setting to True on a per-instance basis. Doesn't this let us have our cake and eat it too?

[Gary Wilson <gary.wilson@…>]

0.96 has been released now, do we want to go forward with this patch?

[Malcolm Tredinnick]

It hasn't been forgotten, Gary, don't worry.

[Jacob]

Adrian and I feel that only the index views (archive_index, object_list) ought to default to allow_empty=True; I should get a 404 visiting (e.g.) a date that doesn't exist.

[mcroydon]

Per jacob's comments, apply allow_empty to generic index views and update docs. Apply patch with -p1.

[mcroydon]

Removing patch needs improvement flag. Should be ready for checkin pending review. Should this be noted in BackwardsIncompatibleChanges?

[Malcolm Tredinnick]

Patch looks fine. Does need a note on the backwards-incompat page when it's committed.

[Malcolm Tredinnick]

(In [6833]) Fixed #685 -- archive_index() and object_list() generic views allow empty
result sets by default now. Thanks, Gary Wilson and Matt Croydon.

This is a backwards incompatible change.