Limit length of first excerpt in the loop

Question

Searched everywhere but have not seem this come up. I'm looking to set the length of the excerpts in the loop in functions.php but I need the first post only to have double the characters as the rest.

Example: 1st post set to 60 characters, following posts set to 30.

I tried this but it doesn't work:

function custom_excerpt_length( $length ) 
{
    static $instance = 0;
    return ( in_the_loop() && 0 == $instance++ ) ? 60 : 30;
}
add_filter( 'excerpt_length', 'custom_excerpt_length' );

Any ideas?

Answer 1

To determine where you are inside the loop in this filter, you will have to access the global main query. Like this:

add_filter ('excerpt_length', 'wpse268679_custom_excerpt_length');

function wpse268679_custom_excerpt_length ($length) {
  // access main query
  global $wp_query;
  // do this only for the main loop and the first post in the query
  if (is_main_query() && ($wp_query->current_post == 0))
    $length = 60;
  else
    $length = 30;
  return $length;
  }

The above will work for the main loop only. If you have a local loop, you cannot access the query globally, so you will have to build your own excerpt function, which passes the query in stead of the post. This isn't that difficult. Like this:

 wpse268679_custom_excerpt ($query) {
   if ($query->current_post == 0)
     $excerpt = wp_trim_words ($query->post->post_excerpt, 60);
   else
     $excerpt = wp_trim_words ($query->post->post_excerpt, 30);
   return $excerpt;
   }

Beware that above will need tweaking, for instance to take into account cases where there is no excerpt defined (in which case you may want to use the post content to trim).