Thanks for the pointer here, John – I think I’m really close to getting this to work.
I am using an ACF field named surname_linked to create a relationship between one term in the surname custom taxonomy and another.
The code below successfully adds a two way relationship between the taxonomy terms, but fails to remove taxonomy terms from the linked term when the term is removed.
Maybe you can spot where I’m going wrong?
/* Bi-directional Surname taxonomy term updating - to keep Surname terms in sync */
function gwsfhs_bidirectional_acf_update_value( $value, $post_id, $field ) {
// vars
$field_name = $field['name'];
$field_key = $field['key'];
$global_name = 'is_updating_' . $field_name;
// bail early if this filter was triggered from the update_field() function called within the loop below
// - this prevents an inifinte loop
if( !empty($GLOBALS[ $global_name ]) ) return $value;
// set global variable to avoid inifite loop
// - could also remove_filter() then add_filter() again, but this is simpler
$GLOBALS[ $global_name ] = 1;
// loop over selected posts and add this $post_id
if( is_array($value) ) {
foreach( $value as $post_id2 ) {
// load existing related posts
$value2 = get_field($field_name, 'surname_'.$post_id2, false);
// allow for selected posts to not contain a value
if( empty($value2) ) {
$value2 = array();
}
$prefix = 'term_';
$post_id = preg_replace('/^' . preg_quote($prefix, '/') . '/', '', $post_id);
// bail early if the current $post_id is already found in selected post's $value2
if( in_array($post_id, $value2) ) continue;
// append the current $post_id to the selected post's 'related_posts' value
$value2[] = $post_id;
// update the selected post's value (use field's key for performance)
update_field($field_key, $value2, 'surname_'.$post_id2);
}
}
// find posts which have been removed
$old_value = get_field($field_name, 'surname_'.$post_id, false);
if( is_array($old_value) ) {
foreach( $old_value as $post_id2 ) {
// bail early if this value has not been removed
if( is_array($value) && in_array($post_id2, $value) ) continue;
// load existing related posts
$value2 = get_field($field_name, 'surname_'.$post_id2, false);
// bail early if no value
if( empty($value2) ) continue;
// find the position of $post_id within $value2 so we can remove it
$pos = array_search($post_id, $value2);
// remove
unset( $value2[$pos] );
// update the un-selected post's value (use field's key for performance)
update_field($field_key, $value2, 'surname_'.$post_id2);
}
}
// reset global varibale to allow this filter to function as per normal
$GLOBALS[ $global_name ] = 0;
// return
return $value;
}
add_filter('acf/update_value/name=surname_linked', 'gwsfhs_bidirectional_acf_update_value', 10, 3);
