Selecting Sub-Category should select parent category.

[sterlo]

If you have the current structure:

• Category A
  • Child Category B

Currently in WordPress if you put any posts into the child category, it will treat as though it's also a part of the parent category.

Meaning that if I don't specifically select the parent category and I just select the child category and save...if I do a query on the parent category - it will have increased in value.

Would it not make sense to have it automatically select all parent categories of a child category when selecting what categories a post belongs to?

[markjaquith]

Some people use parent categories as mere containers, and don't ever want things to show that parent category when the list of categories for that post is output. I don't see this changing — it would be unexpected behavior for a lot of people.

It would be fairly trivial to write a plugin that accomplished this behavior, however. If someone writes one, link to it from this ticket!

[SergeyBiryukov]

​http://wordpress.org/extend/plugins/parent-category-toggler/

[sterlo]

I submit this UseCase without any plugins installed:

Created a parent category and a child category:

mysql> select * from wp_terms; select * from wp_term_taxonomy;

Results (terms):

term_id	name	slug	term_group
22	omgwtfbbq	omgwtfbbq	0
23	lulz	lulz	0

Results (taxonomy):

term_taxonomy_id	term_id	taxonomy	description	parent	count
22	22	category	This is a parent category.	0	0
23	23	category	This is a child of omgwtfbbq.	22	0

I then created a post! Actually...I created three.

One that belongs to the parent category.
One that belongs to the child category (parent no selected).
One that belongs to both.

Now...the terms show up as thus:

select * from wp_term_taxonomy;

term_taxonomy_id	term_id	taxonomy	description	parent	count
22	22	category	This is a parent category.	0	2
23	23	category	This is a child of omgwtfbbq.	22	2

So this reflects your expectation in the form of data.

But if I ask WordPress if the Parent category has posts in it:

$test=get_posts('category_name=omgwtfbbq');
echo count($test);

Result: 3

So if we're going to treat it as though it actually has 3 posts in it...why not...actually have 3 posts in it?

I understand we can right a plugin to "fix" problems. Or we could ... fix the problems.

If this is not a problem, I will defer to your judgment.

[markjaquith]

The default has been that querying the posts in a category queries posts in all subcategories. But there is a difference between being implicitly in a category (due to heritage) and being explicitly in a category (due to user selection). If we checked all parent categories, the distinction between implicit and explicit would be lost.

Consider the hierarchy A > B > C > D. If selecting D selects C, B, and A, a user would have to deselect four boxes to remove a category from D. Or if you do that for them, the interface becomes twitchy when they want a category to be in B and D, but not A and C. People would also suddenly have a lot more categories be shown on their entries — categories they had previously just used as containers.

Real life example: I have Tech, with subcategories WordPress, Photography, and Apple. Tech is for general tech stuff. If it relates to WordPress, Photography, or Apple, I put it in that (but do not select Tech). All four categories' content shows up when browsing to category/tech/. If Tech were automatically selected when I selected WordPress, all WordPress posts would say: "Categories: Tech, WordPress" It's redundant information. And it's not how I categorized it. In the above example, every D post would say: "Categories: A, B, C, D." Every C would say "Categories: A, B, C." If you want a breadcrumb display, you should do that specifically, not have the category system dump every parent in the list along with the explicit category selections.

[sterlo]

Replying to markjaquith:

The default has been that querying the posts in a category queries posts in all subcategories. But there is a difference between being implicitly in a category (due to heritage) and being explicitly in a category (due to user selection). If we checked all parent categories, the distinction between implicit and explicit would be lost.

Thank you!