Fix Bug 1227960 - Add missing top "Previous" link to Revision History

[anaran]

Use same proven logic as "to" radio button.

[anaran]

Evidently things aren't as simple as they could be:

https://travis-ci.org/mozilla/kuma/jobs/93356471#L3303

get_previous is conditional on a mysterious pk property.

Any advice?

[anaran]

The link into the log file does not work for me, I have to scroll to line 3303 manually,

[groovecoder]

Yeah, this is trickier than it should be ...

• The list view uses a custom get_previous transform on the QuerySet to only get approved revisions. (This is old code from SUMO where revisions have to be approved before they are published. On MDN, we auto-approve every revision and rely on post-publish editorial control to catch bad content & actors.) It also skips current_revision.pk == previous_revision.pk which is probably the actual cause of this bug.
• We have a Revision.previous property that we use, but it's expensive because it runs an additional query on the revisions table and sorts it by date to find the latest revision.

I would suggest trying to remove the current_revision.pk == previous_revision.pk condition from the get_previous queryset transform function. Do you have kuma running locally?

[anaran]

No don't have kuma running locally
I'm trying to do small contributions via github and CI.

[groovecoder]

Yeah, that won't work for this one. You'll need to verify it's all working locally too.

[groovecoder]

Closing this unless/until we can verify the get_previous change on a local instance.

If you'd like to try running a local instance, here are the installation docs:

https://kuma.readthedocs.org/en/latest/installation.html