How to get post's current parent term ID?

Question

How do you get the ID of the parent term of the current child term assigned to a post. For a custom taxonomy?

Custom taxonomy: "location"

Countries

• Japan
• USA
• Mexico

Cities

• New York
• Austin

Say we are on a post assigned to "Japan" how do I get the ID of the parent called "Countries"? For this case it doesn't matter if it takes the highest parent or just the direct parent.

I found this:

$term_id = 21;

$child_term = get_term( $term_id, 'location' );
$parent_term = get_term( $child_term->parent, 'location' );

But it doesn't work.

Answer 1

If you just need IDs, get_ancestors will return an array of parents for any type of object:

$term_id = 21;
$ancestors = get_ancestors( $term_id, 'location' );