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function is not described

wp_check_term_hierarchy_for_loops() WP 3.1.0

Checks the given subset of the term hierarchy for hierarchy loops. Prevents loops from forming and breaks those that it finds.

Attached to the 'wp_update_term_parent' filter.

No Hooks.

Return

Int. The new parent for the term.

Usage

wp_check_term_hierarchy_for_loops( $parent, $term_id, $taxonomy );
$parent(int) (required)
term_id of the parent for the term we're checking.
$term_id(int) (required)
The term we're checking.
$taxonomy(string) (required)
The taxonomy of the term we're checking.

Changelog

Since 3.1.0 Introduced.

Code of wp check term hierarchy for loops: wp-includes/taxonomy.php WP 5.2.3

<?php
function wp_check_term_hierarchy_for_loops( $parent, $term_id, $taxonomy ) {
	// Nothing fancy here - bail
	if ( ! $parent ) {
		return 0;
	}

	// Can't be its own parent.
	if ( $parent == $term_id ) {
		return 0;
	}

	// Now look for larger loops.
	if ( ! $loop = wp_find_hierarchy_loop( 'wp_get_term_taxonomy_parent_id', $term_id, $parent, array( $taxonomy ) ) ) {
		return $parent; // No loop
	}

	// Setting $parent to the given value causes a loop.
	if ( isset( $loop[ $term_id ] ) ) {
		return 0;
	}

	// There's a loop, but it doesn't contain $term_id. Break the loop.
	foreach ( array_keys( $loop ) as $loop_member ) {
		wp_update_term( $loop_member, $taxonomy, array( 'parent' => 0 ) );
	}

	return $parent;
}