WordPress Saving translation post when creating new post - php

Question

I wan't to achieve following:
I have to save a duplicate of a newly created post if a user creates a new post (cpt). Afterwards I will set this new post with Polylang to another language as translation for the post created in step one.
Hook into following actions should lead to the desired result:
add_action('new_to_publish', 'duplicate_to_english');
add_action('draft_to_publish', 'duplicate_to_english');
add_action('pending_to_publish', 'duplicate_to_english');
function duplicate_to_english($post)
{
$en_post = pll_get_post($post->ID, 'en');
if(empty($en_post)) {
$new_post = (array) $post;
unset($new_post['ID']);
// INFINITE LOOP
$en_id = wp_insert_post($new_post);
pll_set_post_language($en_id, 'en');
}
}
But unfortunately this will result in an infinite loop (as expected). Now I'm looking for a possibility to avoid this loop. My first idea was to set a $_POST variable and only execute duplication if this variable is set. But I have no idea how to identify a new post. I discovered that WordPress immediately saves an auto-draft on clicking the 'New Post' button so looking for post ID = 0 doesn't work.
Any other approach is highly welcome.

Answer 1

For everyone who needs a solution:
I use the method called to save the meta data to accomplish duplicating my post:
add_action ( 'save_post', 'save_meta', 1, 3 ); // save the custom fields
function save_meta($post_id, $post, $update)
{
// here we check for the transient set in duplicate_post
// if existing delete it end return because we are saving only
// the duplicate. This will avoid infinite loop while saving the
// new translated post
$english = get_transient('saving_english');
if($english) {
delete_transient('saving_english');
return $post->ID;
}
// In case of auto saving draft we can return and don't duplicate the post
if (!wp_verify_nonce($_POST['nonce'], 'nonce')) {
return $post->ID;
}
if (! current_user_can ( 'edit_post', $post->ID )) {
return $post->ID;
}
// collect meta data from $_POST
$item_meta = $_POST['post_meta'];
// Updating meta data for the original post
loop_through_meta($item_meta, $post);
// looking for translated version
$en_id = pll_get_post($post->ID, 'en');
// If the translated post is missing, set transient,
// duplicate the post and category and afterwards write
// the taxonomy entry for polylang
if (empty($en_id)) {
set_transient('saving_english', true);
if ($en_id = duplicate_post($post, $item_meta['title_english'])) {
pll_save_post_translations([
'de' => $post->ID,
'en' => $en_id
]);
}
// If the translated posts already exists deregister the hook
// to avoid infinite loop.
// But note the third parameter priority: It must be the same
// priority as used for registering the hook
} else {
remove_action('save_post', 'save__meta',1);
wp_update_post([
'ID' => $en_id,
'post_title' => $item_meta['title_english']
]);
add_action ( 'save_post', 'save_meta', 1, 3 );
}
// If we have an id save new meta to the translated post
if(!empty($en_id)) {
loopt_through_meta($item_meta, get_post($en_id));
}
}
function duplicate_post ($post, $title)
{
$new_post = (array) $post;
unset($new_post['ID']);
$new_post['post_title'] = $title;
$new_id = wp_insert_post($new_post);
// Here we only need to set the custom category but not
// the Polylang taxonomy.
$taxonomies = get_object_taxonomies($post->post_type);
foreach ($taxonomies as $taxonomy) {
if($taxonomy != 'custom_categories') continue;
$post_terms = wp_get_object_terms($post->ID, $taxonomy, array('fields' => 'slugs'));
wp_set_object_terms($new_id, $post_terms, $taxonomy, false);
}
pll_set_post_language($new_id, 'en');
return $new_id;
}
That's it. Now everytime you create a new post or update an existing post a translated duplicate will be created or updated.