Club Drupal

  function op_empty($field) {

    $this->get_query_fields();

    if (empty($this->query_fields)) {

      return;

    }

    // Add each condition to the custom filter group.

    foreach ((array) $this->query_fields as $query_field) {

      $field = $query_field['field'];

      $this->date_handler = $query_field['date_handler'];

      // Respect relationships when determining the table alias.

      if ($field['table_name'] != $this->table || !empty($this->relationship)) {

        $this->related_table_alias = $this->query->ensure_table($field['table_name'], $this->relationship);

      }

      else {

        $this->related_table_alias = NULL;

      }

      $table_alias = !empty($this->related_table_alias) ? $this->related_table_alias : $field['table_name'];

      $field_name = $table_alias . '.' . $field['field_name'];

      parent::op_empty($field_name);

    }

  }