WordPress: How to get new post tags

Question

I'm trying to get the list of post tags after saving it.

when the post is saved the first time I get an empty array, but when saved the second time (edited) the tags appears correctly,

here is the code I'm using to get the tags:

add_action( 'save_post', 'collect_tags' );
// ...
function collect_tags($postId){
    $terms = get_object_term_cache( $postId, 'post_tag' );
    if ( false === $terms ) {
        $terms = wp_get_object_terms( $postId, 'post_tag' );
    }
    if( empty( $terms )) {
        $terms = wp_get_post_tags( $postId );
    }
    return $terms;
}

Could anybody please point me to where my mistake is?

I'm using WordPress version 4.7

Answer 1

Try

function collect_tags( $post_id, $post, $update ) {
    $terms = get_object_term_cache( $post_id, 'post_tag' );
    if ( false === $terms ) {
        $terms = wp_get_object_terms( $post_id, 'post_tag' );
    }
    if( empty( $terms )) {
        $terms = wp_get_post_tags( $post_id );
    }

    // --- TEST ---
    $tags = wp_get_post_tags( $post_id );
    print_r( $tags );
    // --- END  ---

    return $terms;
}
add_action( 'wp_insert_post', 'collect_tags', 10, 3 );