Wordpress: get_terms() not returning anything even if terms have objects

Question

Normal behaviour of get_terms is not to return terms if there are no posts assigned to. But this is not the case, I can see terms assigned in admin and also checked the database and all seems fine. Also check this code:

$p = get_post(5018); // correctly returns the post

// works: returns the assigned term
$post_terms = wp_get_post_terms($p->ID, 'solutions_sectors', array("fields" => "all"));

// now the opposite:
$first = $post_terms[0];
$tid = $first->term_id;
// works: gives a list of post ids
$term_posts = get_objects_in_term($tid, 'solutions_sectors');

// still, this will output an empty array:
$terms = get_terms(array('taxonomy' => 'solutions_sectors');

// while this will output the right array (obviously):
$terms = get_terms(array('taxonomy' => 'solutions_sectors', 'hide_empty' => false));

So, my posts do have the terms, but get_terms seems not to realise it. Why?

Please note the following:

• I'm using custom post types with custom taxonomies

• I'm using polylang as the languages plugin (but all the posts and terms seems to be correctly translated and assigned)

Answer 1

Found the problem: the count field of the term_taxonomy table was empty, and this is because I bulk-saved my posts using wp_insert_post() during a custom import.

wp_insert_post() seems to have a bug: it correctly applies specified terms to the new post but doesn't update the term_taxonomy count.

The solutions here is a one-shot call to wp_update_term_count_now()`.

Since I have to retrieve all the terms ids on a file executed prior to the taxonomies creation, I've got to wrap the code in an init action.

add_action('init','reset_counts', 11, 0);
function reset_counts(){
  // I'm currently using polylang so first I get all the languages
  $lang_slugs = pll_languages_list(array('fields' => 'slug'));

  foreach($lang_slugs as $lang){
    $terms_ids = get_terms(array(
      'taxonomy' => 'solutions_sectors'
      ,'fields' => 'ids'
      ,'lang' => $lang
      ,'hide_empty' => false
    ));

    // it's important to perform the is_array check 
    if(is_array($terms_ids)) wp_update_term_count_now($terms_ids, 'solutions_sectors');
  }
}

That did the trick. After running it is important to comment out the init action call.