gistfile1.txt

// Folder.js has folders object and files object
// Here we need to load a Folder's files and update some permission, until there is no folder anymore
function shareFolderRecursively(folderId, permission, next) {
    var processFiles = function(files, next) {
        async.each(
            files,
            function(file, callback) {
                file.permission = permission;
                file.save(callback)
            },
            next
        );
    };

    var processFolders = function(folders, next) {
        async.each(
            folders,
            function(folder, callback){
                shareFolderRecursively(folder.id, permission, callback);
            },
            next
        );
    };

    var folderHandler = function(error, folder) {
        if (error) {
            return next(error);
        }

        async.parallel(
            [
                function (callback) {
                    processFiles(folder.files, callback);
                },
                function (callback) {
                    processFolders(folder.files, callback);
                }
            ],
            function (error, results) {
                if (error) {
                    sails.log.error('Error occurred while processing files / folders!');
                    sails.log.error(error);
                }

                next(error);
            }
        );
    };

    sails.models['folders']
        .findOne(folderId)
        .populate('files')
        .populate('folders')
        .exec(folderHandler);
}