Allowing default category to be applied to all CPT associated to 'category' taxonomy

[enrico.sorcinelli]

This patch allows to apply the default category term also for post types that have the category taxonomy, not only for post.

It's not a too remote case to register new post type and associate it also with the category taxonomy.
Currently in this case, the default_category option value is never applied.

I sent two patches. The first one apply the default category term to all post types associated with the category taxonomy.

If for legacy reason we don't want introduce any behaviour compatibility break - for example with third party plugins - I sent the second one that introduce a new default_category_post_types filter allowing to define for which post types (in addition to post) to set the default_category.

[SergeyBiryukov]

Related: #43517

[desrosj]

This ticket has not received any attention during the 5.2 cycle. With beta 1 tomorrow, going to punt this to 5.3.

[davidbaumwald]

@SergeyBiryukov Can this be reasonably included for version 5.3 Beta 1 tomorrow? If not, can we punt this to 5.4?

[davidbaumwald]

With version 5.3 Beta 1 releasing shortly, this enhancement is being punted to Future Release.

[enrico.sorcinelli]

I just refreshed patches (personally, I prefer the second one with the filter).
I hope the enhancement/fix will be added to 5.5 :-)

[SergeyBiryukov]

In 48043:

Posts, Post Types: Introduce default_category_post_types filter.

The filter allows custom post types associated with the category taxonomy to opt in to requiring a default category, same as regular posts.

Props enrico.sorcinelli.
Fixes #43516.

[desrosj]

Marking this to be called out in the miscellaneous developer focused changes dev note.

[audrasjb]

Dev note published: ​https://make.wordpress.org/core/2020/07/29/miscellaneous-developer-focused-changes-in-wordpress-5-5/