Devise\Support\Sortable\Link::getDirection PHP Method

    protected function getDirection($field, $relationship, $classes, $currentlySorted)
    {
        $currentDirection = 'desc';
        if ($this->Input->has('dir') && $this->Input->get('orderBy') == $field && $this->Input->get('relationship') == $relationship) {
            $currentDirection = $this->Input->get('dir');
            $classes[] = $currentDirection;
        } else {
            if (count($currentlySorted) > 1) {
                $currentDirection = $currentlySorted['dir'];
                $classes[] = $currentDirection;
            } else {
                if ($this->defaultOrderBy != [] && $this->defaultOrderBy[0] == $field && !$this->Input->has('orderBy')) {
                    $currentDirection = isset($this->defaultOrderBy[1]) ? $this->defaultOrderBy[1] : $currentDirection;
                    $classes[] = $currentDirection;
                }
            }
        }
        return array($currentDirection, $classes);
    }