javascript - nodejs - 等待 fs.stat 完成

Question

我有一个从 C# 迁移到 nodejs 的同步过程，它每天检查目录中的某些文件。如果这些文件存在，它会将它们添加到 TAR 文件并将该 TAR 写入不同的目录。在使用 forEach 循环检查任何相关文件时，我努力让我的进程等待循环完成，然后再转到下一个函数，以创建 TAR 文件。

我已经按照建议尝试使用 async 模块 here并按照建议 promise here .没有太大的成功。

通过使用 async 模块，我希望停止执行命令，以便我的循环可以在返回 fileList 数组之前完成。目前，我收到了 TypeError: Cannot read property 'undefined' of undefined。

我的问题:async 是否会停止执行直到我的循环完成，如果是这样我做错了什么？

感谢您的关注，请查看下面我的代码。

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.');
    }
};

Answer 1

Async 是不必要的，按照@I'm Blue Da Ba Dee 的建议使用Promises 和按照由建议的fs.statSync @Cheloid 满足了我的要求。对于可能从此结果中受益的任何人，请参阅下面的代码。

var fs = require('fs'), // access the file system.
    tar = require('tar'), // archiving tools.
    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.
    fileList = [], // create an empty array to hold relevant file names.
    slack = require('./slack.js'); // import Slack notification functionality.

// 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 through each file that is found...
    checkFilesPromise(files).then(function (response) {
        console.log('>>> File(s) detected. Starting archiveFilesPromise.');

        // Archive any relevant files.
        archiveFilesPromise(fileList).then(function (response) {
            console.log('>>> TAR file written.');

            // Send a Slack notification when complete.
            slack('TAR file written.', 'good', response);
        }, function (error) {
            console.log('>>> archiveFilesPromise error: ' + error);
            slack('archiveFilesPromise error:' + error, 'Warning', error);
        });
    }, function (error) {
        console.log('>>> CheckFilesPromise error ' + error);
        slack('CheckFilesPromise error: ' + error, 'Warning', error);
    });
});

var checkFilesPromise = function (files) {
    return new Promise(function (resolve, reject) {
        files.forEach(function (item) {
            // ...check it matches the search parameter...
            if (item.match(searchParameter)) {
                var stats = fs.statSync(item);
                var fileDate = moment(stats.mtime).format('YYYYMMDD');

                // ...and current date e.g. today's date.
                if (fileDate === date) {
                    // Add file to an array of file names.
                    console.log('>>> Date match successful, pushing: ' + item);
                    fileList.push(item);
                    resolve('Success');
                 } else {
                    reject('Failure');
                }
            }
        });
    });
};

var archiveFilesPromise = function (list) {
    return new Promise(function (resolve, reject) {

        if (list.length > 0) {
            // Tar the files in the array to another directory.
            tar.c({}, [list[0], list[1]]).pipe(fs.createWriteStream(destination + date + archiveName));
            resolve('Success');
        } else {
            reject('Failure');
        }
    });
};