elif isinstance(instance, basestring):

            return cls.get_by_repo_name(instance)

        elif instance:

            raise Exception('given object must be int, basestr or Instance'

                            ' of %s got %s' % (type(cls), type(instance)))

    @LazyProperty

    def repos_path(self):

        """

        Get's the repositories root path from database

        """

        q = self.sa.query(RhodeCodeUi).filter(RhodeCodeUi.ui_key == '/').one()

        return q.ui_value

    def repo_scan(self, repos_path=None):

        """

        Listing of repositories in given path. This path should not be a

        repository itself. Return a dictionary of repository objects

        :param repos_path: path to directory containing repositories

        """

        if repos_path is None:

            repos_path = self.repos_path

        baseui = make_ui('db')

        repos = {}

        for name, path in get_filesystem_repos(repos_path, recursive=True):

            # name need to be decomposed and put back together using the /

            # since this is internal storage separator for rhodecode

            name = Repository.url_sep().join(name.split(os.sep))

            try:

                if name in repos:

                    raise RepositoryError('Duplicate repository name %s '

                                          'found in %s' % (name, path))

                else:

                    klass = get_backend(path[0])

                    if path[0] == 'hg' and path[0] in BACKENDS.keys():

                        repos[name] = klass(safe_str(path[1]), baseui=baseui)

                    if path[0] == 'git' and path[0] in BACKENDS.keys():

                        repos[name] = klass(path[1])

            except OSError:

                continue