我正在尝试使用nodeJS构建文件结构索引。我正在使用fs.readir函数来迭代文件，这很好。我的问题是下降到目录结构并返回具有正确结构的完整对象。
我有一个名为identify的简单函数，当给定文件名“myfile.txt”时会返回一个对象{name：“myfile”，类型：“txt”}，这将解释下面这部分函数。 。
我的问题是当我将索引器运行到“me”变量时没有返回任何内容。但是，console.log（results）行确实返回。这让我很困惑。
任何帮助将不胜感激！
indexer =
function(directory){
Self.indexleft++;
var results = {};
Self.client.readdir(directory, function(err,fileLst){
if(err){ return; }
for(var count=0; count < fileLst.length; count++){
var ident = identify(fileLst[count]);
if(ident.type = 'dir'){
var descendant = (directory !== '') ?
directory + '\\' + ident.name : ident.name;
ident.children = indexer(descendant);
}
//directory = (directory.split('\\').pop());
results[ident.name] = ident;
}
console.log(results);
return results;
});
}
var me = indexer(''); console.log(me);
EDIT :: 我实际上已经有了一些工作，虽然它并不像我想的那么优雅。以下是我的所作所为。如果有人对优化有任何建议，我很乐意听到它！
最新（工作）代码：
var events = require('events'),
event = new events.EventEmitter(),
setToValue = function(obj, value, path) {
path = path.split('\\');
for (i = 0; i < path.length - 1; i++)
obj = obj[path[i]];
obj[path[i]] = value;
},
identify = function(file){
var split = file.split('.'),
type = (split.length > 1) ? split.pop() : 'dir',
filename = split.join('.');
return { name: filename, type: type };
};
Indexer = function(cli,dir,callback){
this.client = cli; // File reading client
this.startDir = dir; // Starting directory
this.results = {}; // Result object
this.running = 0; // How many itterations of start() are running
this.start(dir); // Start indexing
this.monit(); // Start never returns anything, monit() checks ever 5 seconds and will fire callback if 0 itterations are running.
this.callbackDone = false; // Checks whether the callback has already been fired. Important in case of interval staggering
this.cb = callback;
}
Indexer.prototype = {
start: function(directory){
var Self = this;
Self.running++;
Self.client.readdir(directory, function(err,fileLst){
if(err){ Self.running--; return; }
for(var count=0; count < fileLst.length; count++){
var ident = identify(fileLst[count]);
var descendant = (directory !== '') ? directory + '\\' + ident.name : ident.name;
if(ident.type === 'dir'){
Self.start(descendant);
}
setToValue(Self.results, ident, descendant);
}
Self.running--;
console.log('running' + Self.running);
});
},
monit: function(){
var Self = this;
Self.intervalA = setInterval(function(){
if(Self.running < 1){
if(!Self.callbackDone){
this.callbackDone=true;
Self.cb(Self.results);
}
clearInterval(Self.intervalA);
}
}, 5000)
}
}
var ix = new Indexer(Self.client,'',function(res){
console.log("Index Complete!");
fs.writeFile(path.join(Self.localLibBase,'/index.json'), JSON.stringify(res), (err)=> {
console.log("FileWrite Complete!");
});
});
返回的对象结构示例：
{
"Applications" : {
"name" : "Applications",
"type" : "dir",
"Microsoft Exchange Server 2007" : {
"name" : "Microsoft Exchange Server 2007",
"type" : "dir",
"Microsoft Exchange Server 2007 SP1" : {
"name" : "Microsoft Exchange Server 2007 SP1",
"type" : "iso"
}
}
}
}
答案 0 :(得分：2)
结果只能异步提供，因此您尝试过早输出结果。内部代码仅在稍后执行。
您可以通过多种方式解决此问题。使用异常代码的一个非常好的解决方案是使用promises。
当你有递归电话时，你也必须用承诺解决这个问题。
注意：注意你在与“dir”的比较中有一个错误：你分配而不是比较。
以下是您的代码的外观：
var indexer = function(directory) {
// return a promise object
return new Promise(function (resolve, reject) {
Self.indexleft++;
var results = {};
Self.client.readdir(directory, function(err,fileLst){
if(err) {
reject(); // promise is rejected
return;
}
// "Iterate" over file list asyonchronously
(function nextFile(fileList) {
if (!fileList.length) {
resolve(results); // promise is resolved
return;
}
var file = fileLst.shift(); // shop off first file
var ident = identify(file);
results[ident.name] = ident;
if(ident.type === 'dir'){ // There was a bug here: equal sign!
var descendant = directory !== ''
? directory + '\\' + ident.name : ident.name;
// recursively call indexer: it is again a promise!
indexer(descendant).then(function (result) {
ident.children = result;
// recursively continue with next file from list
nextFile(fileList);
});
} else {
nextFile(fileLst);
}
})(fileLst); // start first iteration with full list
});
});
};
// Call as a promise. Result is passed async to callback.
indexer('').then(function(me) {
console.log(me);
});
我为您的外部引用创建了一些虚函数，以使这个代码片段起作用：
// Below code added to mimic the external references -- can be ignored
var filesystem = [
"",
"images",
"images\\photo.png",
"images\\backup",
"images\\backup\\old_photo.png",
"images\\backup\\removed_pic.jpg",
"images\\panorama.jpg",
"docs",
"docs\\essay.doc",
"readme.txt",
];
var Self = {
indexLeft: 0,
client: {
readdir: function (directory, callback) {
var list = filesystem.filter( path =>
path.indexOf(directory) == 0
&& path.split('\\').length == directory.split('\\').length + (directory!=='')
&& path !== directory
).map ( path => path.split('\\').pop() );
setTimeout(callback.bind(null, 0, list), 100);
}
}
}
function identify(item) {
return {
name: item,
type: item.indexOf('.') > -1 ? 'file' : 'dir'
};
}
// Above code added to mimic the external references -- can be ignored
var indexer = function(directory) {
// return a promise object
return new Promise(function (resolve, reject) {
Self.indexleft++;
var results = {};
Self.client.readdir(directory, function(err,fileLst){
if(err) {
reject(); // promise is rejected
return;
}
// "Iterate" over file list asyonchronously
(function nextFile(fileList) {
if (!fileList.length) {
resolve(results); // promise is resolved
return;
}
var file = fileLst.shift(); // shop off first file
var ident = identify(file);
results[ident.name] = ident;
if(ident.type === 'dir'){ // There was a bug here: equal sign!
var descendant = directory !== ''
? directory + '\\' + ident.name : ident.name;
// recursively call indexer: it is again a promise!
indexer(descendant).then(function (result) {
ident.children = result;
// recursively continue with next file from list
nextFile(fileList);
});
} else {
nextFile(fileLst);
}
})(fileLst); // start first iteration with full list
});
});
};
// Call as a promise. Result is passed async to callback.
indexer('').then(function(me) {
console.log(me);
});
答案 1 :(得分：0)
你从你拥有的代码中期望返回的对象并不是很明显，但我仍然可以帮助你获得这个对象。
对象的形状很糟糕，因为你使用文件名作为对象的键，但这是错误的。密钥应该是程序已知的标识符，因为文件名几乎可以是任何东西，使用文件名作为密钥是非常糟糕的。
例如，考虑文件是否在您的结构中命名为name
{ "Applications" : {
"name" : "Applications",
"type" : "dir",
"name" : {
"name" : "name"
... } } }
const co = require('co')
const {stat,readdir} = require('fs')
const {extname,join} = require('path')
// "promisified" fs functions
const readdirp = path =>
new Promise ((t,f) => readdir (path, (err, res) => err ? f (err) : t (res)))
const statp = fd =>
new Promise ((t,f) => stat (fd, (err,stats) => err ? f (err) : t (stats)))
// tree data constructors
const Dir = (path, children) =>
({type: 'd', path, children})
const File = (path, ext) =>
({type: 'f', path, ext})
// your function
const indexer = function* (path) {
const stats = yield statp (path)
if (stats.isDirectory ())
return Dir (path, yield (yield readdirp (path)) .map (p => indexer (join (path,p))))
else
return File (path, extname (path))
}
这是一个很好的设计，因为我们没有用任何Self.client纠结目录树构建。解析目录和构建树是它自己的事情，如果你需要一个Object来继承这种行为，还有其他方法可以做到。
好的，让我们设置一个示例文件树，然后运行它
$ mkdir test
$ cd test
$ mkdir foo
$ touch foo/disk.iso foo/image.jpg foo/readme.txt
$ mkdir foo/bar
$ touch foo/bar/build foo/bar/code.js foo/bar/migrate.sql
使用indexer很容易
// co returns a Promise
// once indexer is done, you will have a fully built tree
co (indexer ('./test')) .then (
tree => console.log (JSON.stringify (tree, null, ' ')),
err => console.error (err.message)
)
输出（为简洁而删除了一些\n）
{
"type": "d",
"path": "./foo",
"children": [
{
"type": "d",
"path": "foo/bar",
"children": [
{ "type": "f", "path": "foo/bar/build", "ext": "" },
{ "type": "f", "path": "foo/bar/code.js", "ext": ".js" },
{ "type": "f", "path": "foo/bar/migrate.sql", "ext": ".sql" }
]
},
{ "type": "f", "path": "foo/disk.iso", "ext": ".iso" },
{ "type": "f", "path": "foo/image.jpg", "ext": ".jpg" },
{ "type": "f", "path": "foo/readme.txt", "ext": ".txt" }
]
}
如果您在文件路径上尝试indexer，则不会失败
co (indexer ('./test/foo/disk.iso')) .then (
tree => console.log (JSON.stringify (tree, null, ' ')),
err => console.error (err.message)
)
输出
{ "type": "f", "path": "./foo/disk.iso", "ext": ".iso" }