wp query get ids

1/**
2 * Return an array of post IDs
3 *
4 * Build a more efficient query by only returning an array of post IDs.
5 *
6 * @author David Egan
7 * @return array Array of post IDs
8 * @see http://codex.wordpress.org/Class_Reference/WP_Query#Return_Fields_Parameter
9 */
10function carawebs_student_questionnaire_results(){
11
12  $args = array(
13    'post_type'     => 'questionnaire-result',
14    'post_status'   => 'publish',
15    'fields'        => 'ids',
16    'meta_query'    => array(
17      array(
18        'key'        => 'user_type',
19        'value'      => 'student',
20        'compare'    => '=',
21        'type'       => 'CHAR',
22      ),
23    ),
24  );
25
26  // The Query
27  $result_query = new WP_Query( $args );
28
29  $ID_array = $result_query->posts;
30
31  // Restore original Post Data
32  wp_reset_postdata();
33
34  return $ID_array;
35
36}