我有一个同步过程,我正在从C#迁移到nodejs,每天都会为某些文件检查一个目录。如果这些文件存在,则将它们添加到TAR文件中,并将该TAR写入其他目录。在使用forEach
循环检查任何相关文件的同时,我正努力让我的进程在转到下一个函数之前等待循环完成,以创建TAR文件。nodejs - 等待fs.stat完成
我已经尝试使用async
模块作为建议here并承诺建议here。没有太大的成功。
通过使用async
模块,我希望暂停执行命令,以便在返回fileList
数组之前完成循环。目前,我收到了TypeError: Cannot read property 'undefined' of undefined
。
我的问题:将async
暂停执行,直到我的循环完成,如果是的话,我做错了什么?
感谢您的关注,请参阅下面的代码。
var fs = require('fs'), // access the file system.
tar = require('tar'), // archiving tools.
async = require('async'), // async tool to wait for the process's loop to finish.
moment = require('moment'), // date/time tools.
source = process.env.envA, // environment variable defining the source directory.
destination = process.env.envB, // environment variable defining the destination directory.
archiveName = process.env.envArc, // environment variable defining the static part of the TAR file's name.
searchParameter = process.env.env1, // environment variable defining a file search parameter.
date = moment().format('YYYYMMDD'); // Create a date object for file date comparison and the archive file name.
// Change working directory the process is running in.
process.chdir(source);
// Read the files within that directory.
fs.readdir(source, function (err, files) {
// If there is an error display that error.
if (err) {
console.log('>>> File System Error: ' + err);
}
// **** LOOP ENTRY POINT ****
// Loop through each file that is found,
// check it matches the search parameter and current date e.g. today's date.
CheckFiles(files, function (fileList) {
// If files are present create a new TAR file...
if (fileList > 0) {
console.log('>>> File detected. Starting archiveFiles process.');
archiveFiles(fileList);
} else { // ...else exit the application.
console.log('>>> No file detected, terminating process.');
//process.exit(0);
}
});
});
var CheckFiles = function (files, callback) {
console.log('>>> CheckFiles process starting.');
var fileList = []; // Create an empty array to hold relevant file names.
// **** THE LOOP IN QUESTION ****
// Loop through each file in the source directory...
async.series(files.forEach(function (item) {
// ...if the current file's name matches the search parameter...
if (item.match(searchParameter)) {
// ...and it's modified property is equal to today...
fs.stat(item, function (err, stats) {
if (err) {
console.log('>>> File Attributes Error: ' + err);
}
var fileDate = moment(stats.mtime).format('YYYYMMDD');
if (fileDate === date) {
// ...add to an array of file names.
fileList.push(item);
console.log('>>> Date match successful: ' + item);
} else {
console.log('>>> Date match not successful:' + item);
}
});
}
}), callback(fileList)); // Once all the files have been examined, return the list of relevant files.
// **** END LOOP ****
console.log('>>> CheckFiles process finished.');
};
var archiveFiles = function (fileList) {
console.log('>>> Starting archiveFiles process.');
if (fileList.length > 0) {
// Tar the files in the array to another directory.
tar.c({}, [fileList[0], fileList[1]]).pipe(fs.createWriteStream(destination + archiveName));
// TODO Slack notification.
console.log('>>> TAR file written.');
}
};
“承诺”呢? https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Promise – Lucas
嗨@我是Blue Da Ba Dee我已经按照您的建议重构了使用promise的代码,但是@Cheloide指出:由于'fs.stat'的异步性质,我还没有完全修复它。 –