WP_Tax_Query->clean_query removes taxonomy term being searched for

[israelshirk]

When querying using a tax_query on a hierarchical taxonomy, WP_Tax_Query->clean_query() removes the term ID passed in.

So if I have a taxonomy which is structured like this:

Australia
--Sydney
----East Sydney
----West Sydney
----Whatever else

And objects which are tagged with East, West, and then some are just Sydney.

Now in the parse_query filter we do something like this to include objects tagged as Sydney and its children:

$terms = $state->term_id;

$tax_query[] = Array(
    'taxonomy' => 'location',
    'field' => 'id',
    'terms' => Array($term)
);

$wp_query->set("tax_query", $tax_query);

When clean_query runs through the query, it will remove the term_id for Sydney and replace it with the IDs for East Sydney, West Sydney, and the rest of Sydney's children. This results in any objects only tagged with Sydney not being returned by the query.

Changing line 736 of wp-includes/taxonomy.php from:

$query['terms'] = $children;

to:

$query['terms'] = array_merge($query['terms'], $children);

makes it behave as expected.

Or.... I could be in the wrong place entirely :)

Yep, it's a bug. Care to upload the patch?

Patched.

Those unit tests pass without the patch. That's because clean_query() does this:

$children[] = $term;

The patch doesn't seem necessary.

​[UT1085]

Yeah, ryan is right. The only thing the patch does is put the parent terms before the child terms, which makes no difference for the query results.