src/Pool.php
public function getEscapedTypeOrderBy($type)
    {
        return $this->getTypeProperty($type, 'escaped_order_by', function () use ($type) {
            $table_name = $this->getTypeTable($type, true);

            return implode(',', array_map(function ($field_name) use ($table_name) {
                if (substr($field_name, 0, 1) == '!') {
                    return $table_name . '.' . $this->connection->escapeFieldName(substr($field_name, 1)) . ' DESC';
                } else {
                    return $table_name . '.' . $this->connection->escapeFieldName($field_name);
                }
            }, $this->getTypeOrderBy($type)));
        });
    }
public function getEscapedTypeOrderBy($type)
    {
        return $this->getTypeProperty($type, 'escaped_order_by', function () use ($type) {
            $table_name = $this->getTypeTable($type, true);

            return implode(',', array_map(function ($field_name) use ($table_name) {
                if (substr($field_name, 0, 1) == '!') {
                    return $table_name . '.' . $this->connection->escapeFieldName(substr($field_name, 1)) . ' DESC';
                } else {
                    return $table_name . '.' . $this->connection->escapeFieldName($field_name);
                }
            }, $this->getTypeOrderBy($type)));
        });
    }
Return escaped list of fields that we can order by.

@param  string $type
@return string