在将数据从读取流传输到写入流之后从“完成”事件返回值

Question

我正在尝试创建一个读取流，然后将 word 文档 XML 文件的内容通过管道传输到写入流，然后从完成的写入流中读取。我遇到的问题是，在第一个读取、写入和读取的序列中，我得到一个[Error: ENOENT: no such file or directory, open] 错误。但是，在第一次尝试创建此文件后，代码运行平稳并按预期返回 pageCount 值。 我试图从完成的文件中读取，然后在“完成”事件中返回 pageCount 值，但这只会给我留下一个未定义的返回值。因此，我不确定该怎么做。

对于这位苦苦挣扎的小辈，我们将不胜感激。

更新，以下代码对我有用。

  console.log("unzipping");
  const createWordOutput = new Promise((resolve, reject) => {
    console.log("end is firing");
    fs.createReadStream(data)
      .pipe(unzipper.Parse())
      .on("entry", async function (entry) {
        const fileName = entry.path;
        const type = entry.type;
        const size = entry.vars.uncompressedSize;
        //docProps has the meta data of the document, the word/document.xml is the actual document
        if (fileName === "docProps/app.xml") {
          // console.log(fileName);
          entry.pipe(fs.createWriteStream("./wordOutput")).on("finish", () => {
            console.log("finished writing the file");
            console.log("resolving");
            return resolve();
          });
          //once the piping is completed and the XML structure is fully writen a 'finish' event is emitted. This event accepts a callback. Here I put the cb and call readTheFile on the ./output file. This successfully reads the metadata of each file
        } else {
          entry.autodrain();
        }
      });
  });
  await createWordOutput;

  const pageCount = await readWordFile("./wordOutput");
  if (pageCount === undefined) {
    console.log("PAGECOUNT IS UNDEFINED");
  }

  console.log("logging page count in unzip the file");
  console.log(pageCount);
  return pageCount;
};```

Answer 1

错误来自readWordFile，因为它在流完成之前运行。 您需要将阅读移至finish 部分

试试这个：

console.log("unzipping");
let pageCount = "";
fs.createReadStream(data)
    .pipe(unzipper.Parse())
    .on("entry", function(entry) {
        const fileName = entry.path;
        const type = entry.type;
        const size = entry.vars.uncompressedSize;
        if (fileName === "docProps/app.xml") {
            // console.log(fileName);
            entry.pipe(fs.createWriteStream("./wordOutput")).on("finish", async() => {
                console.log("finished writing the file");

                // finished writing, do everything here, and return
                pageCount = await readWordFile("./wordOutput");
                if (pageCount === undefined) {
                    console.log("PAGECOUNT IS UNDEFINED");
                }
                console.log("logging page count in unzip the file");
                console.log(pageCount);
                return pageCount;

            });
        } else {
            entry.autodrain();
        }
    });

};



const readWordFile = (data) => {
    return new Promise(async(resolve, reject) => {

        console.log("this is the data that readWordFile received");
        console.log(data);
        console.log("reading word file");
        const XMLData = await fsp.readFile(data, {
            encoding: "utf-8"
        });
        console.log(XMLData);
        const pageCount = XMLData.split("<Pages>")
            .join(",")
            .split("</Pages>")
            .join(",")
            .split(",")[1];
        console.log("getting page count from read word file");
        console.log(pageCount);
        resolve(pageCount);
    });
};