public function previous($field = 'datepublish', $where = [])
    {
        list($field, $asc) = $this->app['storage']->getSortOrder($field);

        $operator = $asc ? '<' : '>';
        $order = $asc ? ' DESC' : ' ASC';
        $value = isset($this->values[$field]) ? $this->values[$field] : null;

        $params = [
            $field         => $operator . $value,
            'limit'        => 1,
            'order'        => $field . $order,
            'returnsingle' => true,
            'hydrate'      => true,
        ];

        $pager = [];
        $previous = $this->app['storage']->getContent($this->contenttype['singular_slug'], $params, $pager, $where);

        return $previous;
    }