节点：将数据从中间件发送到函数

Question

我正在使用 express，我需要创建一些用于验证的中间件和

我有类似的东西

代码：

app.use(‘/upload', fromData)
app.use(‘/upload', function firstUpload(req, res, next) {
    return fileHandler(req, res, next)
        .then((status) => {
            res.statusCode = 201;
            res.end(status)
        }).catch((err) => {
            return next(new appError(500, err));
        });
});

现在我使用另一个函数 fromHandler

function formData(req) {

 return new Promise((resolve, reject) => {
 const form = new formidable.IncomingForm();
  form.maxFileSize = 100 * 1024 * 1024;
  form.keepExtensions = true;
  form.multiEntry = true;
  form.parse(req, (err, fields, files) => {
    const filesInfo = Object.keys(files).map((key) => {
        const file = files[key];
        const filePath = file.path;
        const fileExt = path.extname(file.name);
        const fileName = path.basename(file.name, fileExt);
        return {filePath, fileExt};
    });
 }
  Resolve(filesInfo)
}

我需要的是从formData函数返回数据Resolve(filesInfo)到 fileHandler 函数，我该怎么做？ fileHandler函数需要获取filesInfo

Answer 1

你在这里不需要承诺。中间件使用next 函数作为callback 转到下一个处理程序。在此之前，您应该将中间件中的数据放入 req 对象中。之后，您可以通过从req. filesInfo获取来使用。

function formData(req, res, next) {
  const form = new formidable.IncomingForm();
  form.maxFileSize = 100 * 1024 * 1024;
  form.keepExtensions = true;
  form.multiEntry = true;
  form.parse(req, (err, fields, files) => {
    if (err || fields.length === 0) {
       res.status(500).json({ message: 'you are done' }); // <- this is where you stop the request with an error.
    }
    const filesInfo = Object.keys(files).map((key) => {
        const file = files[key];
        const filePath = file.path;
        const fileExt = path.extname(file.name);
        const fileName = path.basename(file.name, fileExt);
        return {filePath, fileExt};
    });
    req.filesInfo = filesInfo;
    next();
  }
}

function fileHandler(req, res) {
  console.log(req.filesInfo); /* <- you can also get the filesInfo here */ 
  return Promise.resolve({});
}

app.use(‘/upload', fromData)
app.use(‘/upload', function(req, res, next) {
    // console.log(req.filesInfo); => You can get your filesInfo here and do whatever you want
    return fileHandler(req, res, next)
        .then((status) => {
            res.statusCode = 201;
            res.end(status)
        }).catch((err) => {
            return next(new appError(500, err));
        });
});