[zaino]

I have tried this from the codex and it works great for xprofile fields, however I do not know how to modify it for ACF fields. There is a whole block of code in there specific to xprofile fields and I have tried various modifications, none working. Would love to get some concrete guidance. Thanks.

function my_custom_ids( $field_name, $field_value = '' ) {
  
  if ( empty( $field_name ) )
    return '';
  
  global $wpdb;
  
  $field_id = xprofile_get_field_id_from_name( $field_name ); 
 
  if ( !empty( $field_id ) ) 
    $query = "SELECT user_id FROM " . $wpdb->prefix . "bp_xprofile_data WHERE field_id = " . $field_id;
  else
   return '';
  
  if ( $field_value != '' ) 
    $query .= " AND value LIKE '%" . $field_value . "%'";
      /* 
      LIKE is slow. If you're sure the value has not been serialized, you can do this:
      $query .= " AND value = '" . $field_value . "'";
      */
  
  $custom_ids = $wpdb->get_col( $query );
  
  if ( !empty( $custom_ids ) ) {
    // convert the array to a csv string
    $custom_ids_str = 'include=' . implode(",", $custom_ids);
    return $custom_ids_str;
  }
  else
   return '';
   
}