Parameterized feeds have incorrect 404 behavior

[niran@…]

When using the syndication framework to generate parameterized feeds as described in the ​documentation, leaving off the parameter from the URL causes an exception to be raised in the Feed's link() function.

For example, if I'm trying to generate per-tag feeds for a blog at /feeds/tags/TAG_NAME, /feeds/tags/ will cause an AttributeError in my Feed subclass' link() function because the object passed to it is None. My proposed solution, which seems to work for me, is instead of checking the contents of url in get_feed(), we should check if the Feed class (self) has a get_object function, since from what I understand, any Feed subclass with a get_object() function is intended to generate a parameterized feed.

With my patch applied, /feeds/tags/ results in a 404, which seems like the appropriate behavior to me.

[niran@…]

patch

[Malcolm Tredinnick]

This change in behaviour isn't a good idea. It would prevent having feeds that handle both parameterised and non-parameterised versions, as we currently permit (and as I'm using in code of my own, so I know it's possible).

I will update the example documentation to have better error handling, though.

[Niran Babalola <niran@…>]

Okay, here's a cleaner patch that maintains the ability to handle both parameterized and non-parameterized feeds in the same class.

[Niran Babalola <niran@…>]

revised patch

[Malcolm Tredinnick]

Yes, this might be a reasonably approach. I want to think about it a bit to see if there are any drawbacks, but it might well work.

[MichaelBishop]

Design decision needed. Are there any drawbacks to this approach?

[Malcolm Tredinnick]

(In [7295]) Added more robust processing to parameterised syndication feeds for the case
when all the "extra" URL bits are accidentally omitted. Patch from Niran
Babalola <niran@…>. Fixed #5855.

[Malcolm Tredinnick]

(In [7328]) Merged the tests and documentation from #4720 to support the changes in [7295].
Thanks, Andy Gayton. Fixed #4720. Refs #5855.