如何在遍历一系列目录的循环中使用异步 readdir 函数？

Question

我正在从多个目录中归档某些文本文件。所以首先，我在一个文件夹内迭代，它给我 folderPath 并且这个 folderPath 可以包含许多文件（txt、pdf 等）并且有多个文件夹路径，我正在为 folderPath 使用异步 readdir 并将这些单独的文件附加到归档器，然后最后关闭。如果我在文件夹循环结束之前执行 archive.finalize，它不会在 zip 中生成所需数量的 txt 文件，而只是初始文件，这很明显。如果我在第 2 行保留 archive.finalize，它会抛出一个错误，如目录结构下方所述。有人可以在这方面提供帮助吗？

Directory structure is like:

mainfolder/folder1 mainfolder/folder2

mainfolder/folder1/sometext.txt mainfolder/folder1/someanothertext.txt

mainfolder/folder2/sometext.txt mainfolder/folder2/someanothertext.txt

Now I want to zip it as:

Outuput.zip which contains -> folder1 and folder2 with respective txt files. I was able to achieve it when using sync function to readdir(readdirsync), but with async, I am facing some callback issue.

错误：

ArchiverError: queue closed
    at Archiver.file (C:\Users\Workspace\code\node_modules\archiver\lib\core.js:692:24)
    at C:\Users\Workspace\current_code_snippet
    at Array.forEach (<anonymous>)
    at C:\Users\current_code_snippet_ line 3 as specified in code snippet
    at FSReqCallback.oncomplete (fs.js:156:23) {
  code: 'QUEUECLOSED',
  data: undefined
}

代码：

this.children.forEach((value, _index, _array) => {
    const folderPath = path.join(basePath, value);
    fs.readdir(folderPath, (err, fileNames) => {
          if (err){
              throw err;
          }
          else {
            fileNames.forEach(file => {  // line 3
              if (outputType === ".txt") {
                  const filePath = path.join(basePath, value, file);
                  archive.file(filePath, { name: `${value}/${file}` }); // file is saved as value/file inside parent zip
              }
            })
          }
    })
    archive.finalize(); // line 1
});
archive.finalize(); // line 2

Answer 1

我会将 fs 调用包装到 Promise 中。这使得只等待操作成为可能，并且它减少了代码的一些复杂性。

请注意 forEach 循环不适用于 async, await

const children = ["path_0", "path_1", "path_2", "path_3"];

// mock fs / async action
const fs = {
    readdir: (path, error, success) => {
        setTimeout(() => {
            success(["file_0", "file_1", "file_2"]);
        }, Math.random() * 1000);
    }
}

// function I would add to make the process simpler
const readFiles = (path) => {
    return new Promise(res => {
        fs.readdir(path, () => {}, (s) => {
            res(s);
        });
    });
}
// start helper as async
const start = async() => {
    // first await all files to be added to the archive
    await Promise.all(children.map(async child => {
        const files = await readFiles();
        // loop to add all files to the zip
        // archive.file(filePath, { name: `${value}/${file}` });
        console.log(child, files);
    }));
    // then archive all files
    // archive.finalize();
    console.log("finalize archive");
}
start();

如何在遍历一系列目录的循环中使用异步 readdir 函数？

How to use async readdir function inside a loop iterating over series of directories?

javascript

archive

node.js

typescript