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wp_check_term_hierarchy_for_loops( int $parent, int $term_id, string $taxonomy )

Checks the given subset of the term hierarchy for hierarchy loops.

Description

Prevents loops from forming and breaks those that it finds.

Attached to the ‘wp_update_term_parent’ filter.

Parameters

$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.

Return

(int) The new parent for the term.

Source

File: wp-includes/taxonomy.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.
	$loop = wp_find_hierarchy_loop( 'wp_get_term_taxonomy_parent_id', $term_id, $parent, array( $taxonomy ) );
	if ( ! $loop ) {
		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;
}

Uses

Uses Description
wp-includes/functions.php: wp_find_hierarchy_loop()

Find hierarchy loops using a callback function that maps object IDs to parent IDs.
wp-includes/taxonomy.php: wp_update_term()

Update term based on arguments provided.

Changelog

Version Description
3.1.0 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/wp_check_term_hierarchy_for_loops