/**
* Sets an author on a post, with a specified role.
*
* This can be used to edit an existing coauthor - for example, changing the role
* of an author already attached to a post - but it is not guaranteed to
* preserve order. If the sorted order of authors needs to be preserved, call
* `update_coauthors_on_post()` and pass the full list of coauthors to update,
* sorted.
*
* @param int|object $post_id Post to set author as "coauthor" on
* @param object|string $author user_nicename of Author to add on post (or WP_User object)
* @param object|string $author_role Term or slug of contributor role to set. Defaults to "byline" if empty
* @return bool True on success, false on failure (if any of the inputs are not acceptable).
*/
function set_author_on_post($post_id, $author, $author_role = false)
{
global $coauthors_plus;
if (is_object($post_id) && isset($post_id->ID)) {
$post_id = $post_id->ID;
}
$post_id = intval($post_id);
if (is_string($author)) {
$author = $coauthors_plus->get_coauthor_by('user_nicename', $author);
}
if (!isset($author->user_nicename)) {
return false;
}
// Only create the byline term if the contributor role is:
// - one of the byline roles, as set in register_author_role(), or
// - unset, meaning they should default to primary author role.
if (!$author_role || in_array($author_role, byline_roles())) {
$coauthors_plus->add_coauthors($post_id, array($author->user_nicename), true);
}
if (!$post_id || !$author) {
return false;
}
foreach (get_post_meta($post_id) as $key => $values) {
if (strpos($key, 'cap-') === 0 && in_array($author->user_nicename, $values)) {
delete_post_meta($post_id, $key, $author->user_nicename);
}
}
if (!is_object($author_role)) {
$author_role = get_author_role($author_role);
}
if (!$author_role) {
return false;
}
add_post_meta($post_id, 'cap-' . $author_role->slug, $author->user_nicename);
}
/**
* Update the co-authors on a post on saving.
*
* @param int $post_ID
* @param array $new_coauthors Array of strings in the format "{nicename}|||{role}"
* as posted by the sortables in the meta box.
*/
function update_coauthors_on_post($post_id, $new_coauthors)
{
global $coauthors_plus;
$post = get_post($post_id);
if (!$coauthors_plus->is_post_type_enabled($post->post_type)) {
return;
}
if ($new_coauthors && is_array($new_coauthors)) {
// Convert the new coauthors array from the string format used on inputs from the post edit
// screen into proper objects which can be compared with existing coauthors.
$new_coauthors = array_filter(array_map(function ($coauthor_string) {
global $coauthors_plus;
list($author_name, $role) = explode('|||', $coauthor_string);
// Empty roles can come in either as the string "byline",
// or as an empty string. Handle them both the same.
if ($role === 'byline') {
$role = '';
}
$new_coauthor = $coauthors_plus->get_coauthor_by('user_nicename', sanitize_text_field($author_name));
if ($new_coauthor) {
$new_coauthor->author_role = sanitize_text_field($role);
return $new_coauthor;
}
}, $new_coauthors));
// Diff new data against the already added coauthors. If they aren't identical, wipe the old postmeta and re-add.
$existing_coauthors = get_coauthors($post_id, array('author_role' => 'any'));
$difference = false;
for ($i = 0; $i <= max(count($new_coauthors), count($existing_coauthors)); $i++) {
if (!isset($new_coauthors[$i]) || !isset($existing_coauthors[$i])) {
$difference = true;
break;
}
if ($new_coauthors[$i]->user_nicename !== $existing_coauthors[$i]->user_nicename) {
$difference = true;
break;
}
if ($new_coauthors[$i]->author_role !== $existing_coauthors[$i]->author_role) {
$difference = true;
break;
}
}
if ($difference) {
remove_all_coauthor_meta($post_id);
foreach ($new_coauthors as $new_coauthor) {
set_author_on_post($post_id, $new_coauthor, $new_coauthor->author_role);
}
}
// Use $coauthors_plus->set_coauthors to update byline roles. This clears the existing terms and
// re-adds them in the correct order.
$new_byline_coauthors = array_filter($new_coauthors, function ($author) {
return empty($author->author_role) || in_array($author->author_role, byline_roles());
});
$byline_coauthors_slugs = wp_list_pluck($new_byline_coauthors, 'user_nicename');
$coauthors_plus->add_coauthors($post_id, $byline_coauthors_slugs, false);
}
}