wp_terms_checklist() returns all non-hierarchical terms even with $descendants_and_self parameter

[helgatheviking]

Granted, I know that wp_terms_checklist() is meant for hierarchical terms, but I am also using it on non-hierarchical terms in my Radio Buttons for Taxonomies plugin. I was trying to use all core scripts/ajax-callbacks for the "add new term" feature in a posts taxonomy metabox, but it turns out that WP_Lists calls _wp_ajax_add_hierarchical_term via ajax which returns wp_terms_checklist() as part of the result.

For hierarchical terms the descendants_and_self parameter limits the size of the returned checklist. For non-hierarchical terms, however, I found that it simply returns *all* terms in addition to the new term.

wp_terms_checklist( $post_id, array('descendants_and_self' => $term_id ));

Obviously this isn't major, but it seems to me that if descendants_and_self is set, but there are no descendants... it should just return the single term.

I've gotten around this by unhooking that ajax callback for non-hierarchical terms and substituting my own that returns just a single input.

Here's the pertinent part of wp_terms_checklist():

if ( $descendants_and_self ) {
		$categories = (array) get_terms($taxonomy, array( 'child_of' => $descendants_and_self, 'hierarchical' => 0, 'hide_empty' => 0 ) );
		$self = get_term( $descendants_and_self, $taxonomy );
		array_unshift( $categories, $self );
	} else {
		$categories = (array) get_terms($taxonomy, array('get' => 'all'));
	}

I think if for non-hierarchical terms we skipped the get_terms() call we could limit the returned checklist to a single term.

if ( $descendants_and_self ) {
		$categories = is_taxonomy_hierarchical( $taxonomy ) ? (array) get_terms($taxonomy, array( 'child_of' => $descendants_and_self, 'hierarchical' => 0, 'hide_empty' => 0 ) ) : array();
		$self = get_term( $descendants_and_self, $taxonomy );
		array_unshift( $categories, $self );
	} else {
		$categories = (array) get_terms($taxonomy, array('get' => 'all'));
	}

[MikeHansenMe]

patch based on suggestion, includes unit test

[boonebgorges]

Thanks for the patch, MikeHansenMe. Can you provide a test that uses a non-hierarchical taxonomy? That's the change that really needs coverage here. (Ideally we'd keep the test you have here too, but add some real data so that we're returning more than just the Uncategorized category - maybe register a new hierarchical taxonomy so we don't have to deal with the quirks of 'category'.)

[MikeHansenMe]

Yea, I will work up a few other tests.

[MikeHansenMe]

more tests

[boonebgorges]

Thanks @MikeHansenMe. Can we please move the fixture setup outside of setUp()? Putting it there adds lots of overhead for every test method in the class. It's fine to repeat it in both of the new tests. Also, we should be using self::factory()->term->create() instead of wp_insert_term() when setting up test fixtures.

Regarding the patch, the logic is somewhat convoluted. If the taxonomy is non-hierarchical, there's no point in doing the array_unshift() stuff at all - $categories should just be array( $term ). Can we simplify a bit?

[MikeHansenMe]

Hey @boonebgorges I will take a better look at what it is actually doing. I was just refreshing what already existed.

[boonebgorges]

@MikeHansenMe Thank you, sir!