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javascript - 从多级 JSON 递归创建目录(使用 async.js)

转载 作者:行者123 更新时间:2023-11-30 10:37:25 25 4
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定义

File#createDirectoriesFromJSON (json, cb);

json:JSON对象。

cb:函数。参数:error(错误)、created( bool 值,如果至少创建了一个目录则为true)。

假设 File 类包含一个名为 _path 的属性,其中包含一个目录的路径。


用法

var json = {
b: {
c: {
d: {},
e: {}
},
f: {}
},
g: {
h: {}
}
};

//this._path = "."
new File (".").createDirectoriesFromJSON (json, function (error, created){
console.log (created); //Prints: true

//callback binded to the File instance (to "this"). Hint: cb = cb.bind (this)
this.createDirectoriesFromJSON (json, function (error, created){
console.log (created); //Prints: false (no directory has been created)
});
});


结果

在“.”下json 对象中显示的目录树已创建。

./b/c/d
./b/c/e
./b/f
./b/g/h


实现

这是我没有 async.js 的东西:

File.prototype.createDirectoriesFromJSON = function (json, cb){
cb = cb.bind (this);

var created = false;
var exit = false;

var mkdir = function (path, currentJson, callback){
var keys = Object.keys (currentJson);
var len = keys.length;
var done = 0;

if (len === 0) return callback (null);

for (var i=0; i<len; i++){
(function (key, i){
var dir = PATH.join (path, key);
FS.mkdir (dir, function (mkdirError){
exit = len - 1 === i;

if (mkdirError && mkdirError.code !== "EEXIST"){
callback (mkdirError);
return;
}else if (!mkdirError){
created = true;
}

mkdir (dir, currentJson[key], function (error){
if (error) return callback (error);
done++;
if (done === len){
callback (null);
}
});
});
})(keys[i], i);
}
};

var errors = [];

mkdir (this._path, json, function (error){
if (error) errors.push (error);
if (exit){
errors = errors.length === 0 ? null : errors;
cb (errors, errors ? false : created);
}
});
};

出于好奇,我想使用 async.js 重写函数。这里的问题是函数是递归的和并行的。例如,“b”文件夹是与“g”并行创建的。 “b/c”和“b/f”以及“b/c/d”和“b/c/e”也是如此。

最佳答案

我的尝试:

var _path  = require('path');
var _fs = require('fs');
var _async = require('async');

function File() {
this._path = __dirname + '/test';
}

File.prototype.createDirectoriesFromJSON = function(json, cb) {
var created = [], errors = [];

function iterator(path, currentJson, key, fn){
var dir = _path.join(path, key);

_fs.mkdir(dir, function(mkdirError) {

if(mkdirError && mkdirError.code !== "EEXIST") {
errors.push(mkdirError);
} else if(!mkdirError) {
created.push(dir);
}

mkdir(dir, currentJson[key], fn);
});
}

function mkdir(path, currentJson, callback) {
var keys = Object.keys(currentJson);

if(keys.length === 0) return callback(null);

_async.forEach(keys, iterator.bind(this, path, currentJson), callback);
}

mkdir(this._path, json, cb.bind(this, errors, created));
};


new File().createDirectoriesFromJSON({
b: {
c: {
d: {},
e: {}
},
f: {}
},
g: {
h: {}
}
}, function(errors, successes) {
// errors is an array of errors
// successes is an array of successful directory creation
console.log.apply(console, arguments);
});

测试:

$ rm -rf test/* && node test.js && tree test

[] [ '/Users/fg/Desktop/test/b',
'/Users/fg/Desktop/test/g',
'/Users/fg/Desktop/test/b/c',
'/Users/fg/Desktop/test/b/f',
'/Users/fg/Desktop/test/g/h',
'/Users/fg/Desktop/test/b/c/d',
'/Users/fg/Desktop/test/b/c/e' ] null
test
|-- b
| |-- c
| | |-- d
| | `-- e
| `-- f
`-- g
`-- h

7 directories, 0 files

注意事项:

  • 由于 errors.push(mkdirError); 意味着无法创建目录,因此可以将 return fn(null); 附加到它以停止目录从这个分支创建。
  • cb 将收到始终为 null 的第三个参数。
  • 我最好使用 wrench .mkdirSyncRecursive() 用于此类任务,或 substack async mkdirp .

[更新] 使用 mkdirp 和 lodash(或下划线)代码可以更清晰:

var _path   = require('path');
var _fs = require('fs');

var _async = require('async');
var _mkdirp = require('mkdirp');
var _ = require('lodash'); // or underscore

function File() {
this._path = __dirname + '/test';
}

File.prototype.flattenJSON = function(json){
function walk(path, o, dir){
var subDirs = Object.keys(o[dir]);
path += '/' + dir;

if(subDirs.length === 0){
return path;
}

return subDirs.map(walk.bind(null, path, o[dir]));
}

return _.flatten(Object.keys(json).map(walk.bind(null, this._path, json)));
};

File.prototype.createDirectoriesFromJSON = function(json, cb) {
var paths = this.flattenJSON(json)
, created = []
, errors = [];

function iterator(path, fn){
_mkdirp(path, function(mkdirError) {

if(mkdirError && mkdirError.code !== "EEXIST") {
errors.push(mkdirError);
} else if(!mkdirError) {
created.push(path);
}

return fn(null);
});
}

_async.forEach(paths, iterator, cb.bind(this, errors, created));
};


new File().createDirectoriesFromJSON({
b: {
c: {
d: {},
e: {}
},
f: {}
},
g: {
h: {}
}
}, function(errors, successes) {
// errors is an array of error
// successes is an array of successful directory creation
console.log.apply(console, arguments);
});

测试:

$ rm -rf test/* && node test2.js && tree test

[] [ '/Users/fg/Desktop/test/b/f',
'/Users/fg/Desktop/test/g/h',
'/Users/fg/Desktop/test/b/c/d',
'/Users/fg/Desktop/test/b/c/e' ] null
test
|-- b
| |-- c
| | |-- d
| | `-- e
| `-- f
`-- g
`-- h

7 directories, 0 files

注意:

  • iterator 可以通过使用部分函数应用程序来删除,但是下划线/lodash 只支持从左到右的部分,因此我不想要求另一个库来这样做。

关于javascript - 从多级 JSON 递归创建目录(使用 async.js),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13099033/

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