How to set the current post in WordPress?

Question

WordPress

WordpPress has a get_next_post() function that returns the next post.
Question: in order to return the next post, WordPress needs to know the current one, how to set this current post itself, knowing the post ID, in order to use the get_next_post () function?

Answer 1

The get_next_post() function works in the_post() loop. In order to install the current post on your own, you need to create an additional loop and get the link you are interested in in it, for example:

$myid = 999;
$next_post = '';
$previous_post = '';

$args = array('p'=> $myid, 'post_type' => 'any');
$my_posts = new WP_Query($args);
if($my_posts){
  foreach( $my_posts as $post ){
    $next_post = get_next_post_link();
    $previous_post = get_previous_post_link();
  }
}
wp_reset_postdata();

Or like this:

$myid = 999;
$next_post = get_around_post ($myid, 'ASC');
$previous_post = get_around_post ($myid, 'DESC');

function get_around_post ($custom_id, $side){
  global $posts;
  $category = get_the_category();
  rsort( $category );
  $cat_add_id = $category[0]->term_id;
  $around_post = '';
  $my_posts = get_posts( array(
    'cat' => $cat_add_id,
    'posts_per_page' => 1,
    'exclude' => $custom_id,
    'order' => $side,
  ) );

  if( $my_posts ){
    foreach( $my_posts as $post ){
      $around_post = '<a href="'.get_permalink($post->ID).'">'.$post->post_title.'</a>';
    }
  }
  wp_reset_postdata();
  return $around_post;
}