向multer-s3路由发送POST请求时出现500错误

Question

我正在尝试使用S3（特别是multer-s3）为当前具有multer /文件系统文件上传功能的传统Web应用程序上传图像（在S3上传失败之前，GitHub仓库带有以前的代码）尝试here）。该应用程序已部署到具有临时文件存储功能的Heroku中，因此旧设置不再可行。

我根据本教程https://www.youtube.com/watch?v=ASuU4km3VHE&t=1364s尝试使用multer-s3来完成此操作，但是最多花了20分钟的时间，试图将POST请求发送到新的图像上传路线，但500错误，而在本教程中，响应中提供了一个AWS映像路径。

这是我到目前为止尝试过的：

我创建了一个存储桶，并获取了访问代码和密钥。在我的S3存储桶设置中，在权限->阻止公共访问下，将所有设置都关闭。我还按照Heroku here的建议添加了CORS配置代码（但如果没有它，我仍然会出现500错误）。

在util文件夹中，使用以下代码添加了一个名为file-upload.js的文件（我将Nodemon.json文件用作配置键）：

const aws = require('aws-sdk');
const multer = require('multer');
const multerS3 = require('multer-s3');
const { uuid } = require('uuidv4');
 
aws.config.update({
  secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  accessKeyId: process.env.AWS_ACCESS_KEY_ID,
  region: 'us-west-2',
});
 
const s3 = new aws.S3();
 
const upload = multer({
  storage: multerS3({
    s3,
    bucket: 'nodejs-shop',
    acl: 'public-read',
    // Called when saving image to AWS
    metadata(req, file, cb) {
      cb(null, { fieldName: file.fieldname });
    },
    // Called before saving image to AWS
    key(req, file, cb) {
      cb(null, uuid());
    },
  }),
});
 
module.exports = upload;

在路由文件夹中，我添加了一个名为file-upload.js的文件，其代码如下：

const express = require('express');
const router = express.Router();
 
const upload = require('../util/file-upload');
 
// Will send image under this key 'image' in request to server
const singleUpload = upload.single('image');
 
router.post('/image-upload', (req, res, next) => {
  // Callback function called after image is uploaded or will get error from server
  singleUpload(req, res, (err) => {
    return res.json({ imageUrl: req.file.location });
  });
});
 
module.exports = router;

在app.js中，我导入了路由文件const fileRoutes = require（'./ routes / file-upload'）;并将中间件添加到authRoutes中间件app.use（fileRoutes）;之后。我还注释了app.js中所有以前使用的multer代码。

当前的app.js代码：

const path = require('path');
const fs = require('fs');
// const https = require('https');

const express = require('express');
const bodyParser = require('body-parser');
const mongoose = require('mongoose');
const session = require('express-session');
const MongoDBStore = require('connect-mongodb-session')(session);
const csrf = require('csurf');
const flash = require('connect-flash');
// const multer = require('multer');
// const { uuid } = require('uuidv4');
const helmet = require('helmet');
const compression = require('compression');
const morgan = require('morgan');

const errorController = require('./controllers/error');
const User = require('./models/user');

const MONGODB_URI =
  // process object is globally available in Node app; part of Node core runtime. The env property contains all environment variables known by process object. Using nodemon.json to store environment variables, but could alternatively use dotenv package for this (see https://www.youtube.com/watch?v=17UVejOw3zA)
  `mongodb+srv://${process.env.MONGO_USER}:${process.env.MONGO_PASSWORD}@cluster0-4yuid.mongodb.net/${process.env.MONGO_DEFAULT_DATABASE}`;

const app = express();
const store = new MongoDBStore({
  uri: MONGODB_URI,
  collection: 'sessions',
});
// Secret used for signing/hashing token is stored in session by default
const csrfProtection = csrf();

// Don't want to start server until file is read in, thus using synchronous version
// const privateKey = fs.readFileSync('server.key');
// const certificate = fs.readFileSync('server.cert');

// Commenting out original file upload method since changed to use AWS S3 for image upload/hosting
// const fileStorage = multer.diskStorage({
//   destination: (req, file, cb) => {
//     // First arg is for error message to throw to inform multer something is wrong with incoming file and it should not store it; with null, telling multer okay to store it
//     cb(null, 'images');
//   },
//   filename: (req, file, cb) => {
//     cb(null, uuid());
//   },
// });

// const fileFilter = (req, file, cb) => {
//   file.mimetype === 'image/png' ||
//   file.mimetype === 'image/jpg' ||
//   file.mimetype === 'image/jpeg'
//     ? cb(null, true)
//     : cb(null, false);
// };

app.set('view engine', 'ejs');
// Setting this explicity even though the views folder in main directory is where the view engine looks for views by default
app.set('views', 'views');

const adminRoutes = require('./routes/admin');
const shopRoutes = require('./routes/shop');
const authRoutes = require('./routes/auth');
const fileRoutes = require('./routes/file-upload');

// Create write stream (for passing to morgan, used to log request data), for logging request data in file instead of console
// flags: 'a': a is for append; new data will be appended to that file (additional log statements are added to end of existing file rather than overwriting it)
const accessLogStream = fs.createWriteStream(
  path.join(__dirname, 'access.log'),
  { flags: 'a' }
);

// Set secure response header(s) with Helmet
// In my app, in developer tools (in the network tab) I can see it added one additional response header for localhost, Strict-Transport-Security. This HTTP header tells browsers to stick with HTTPS and never visit the insecure HTTP version. Once a browser sees this header, it will only visit the site over HTTPS for the next 60 days
app.use(helmet());
// Compress assets. Note: Compression is normally done by hosting providers, but deploying to Heroku which does offer it
app.use(compression());
// Log request data using writable file stream created above. Which data is logged and how to format it is passed into funtion
// Also normally handled by hosting providers
// app.use(morgan('combined', { stream: accessLogStream }));

app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
// Commented out since changed to use AWS S3 for image upload/hosting
// app.use(multer({ storage: fileStorage, fileFilter }).single('image'));
app.use(express.static(path.join(__dirname, 'public')));
app.use('/images', express.static(path.join(__dirname, 'images')));
app.use(
  session({
    secret: 'my secret',
    resave: false,
    saveUninitialized: false,
    store,
  })
);
app.use(csrfProtection);
app.use(flash());

app.use((req, res, next) => {
  // Locals field: Express feature for setting local variables that are passed into views. For every request that is executed, these fields are set for view that is rendered
  res.locals.isAuthenticated = req.session.isLoggedIn;
  res.locals.csrfToken = req.csrfToken();
  next();
});

app.use((req, res, next) => {
  // When you throw an error in synchronous places (outside of callbacks and promises), Express will detect this and execute next error handling middleware. But if error is thrown within async code (in then or catch block), Express error handling middleware won't be executed; app will simply crash; have to use next()
  // throw new Error('sync dummy');
  if (!req.session.user) {
    return next();
  }
  User.findById(req.session.user._id)
    .then((user) => {
      if (!user) {
        return next();
      }
      req.user = user;
      next();
    })
    // catch block will be executed in the case of technical issue (e.g., database down, or insufficient permissions to execute findById())
    .catch((err) => {
      // Within async code snippets, need to use next wrapping error, outside you can throw error
      next(new Error(err));
    });
});

app.use('/admin', adminRoutes);
app.use(shopRoutes);
app.use(authRoutes);
app.use(fileRoutes);

app.get('/500', errorController.get500);

app.use(errorController.get404);

// Error-handling middleware. Express executes this middleware when you call next() with an error passed to it
app.use((error, req, res, next) => {
  // res.status(error.httpStatusCode).render(...);
  // res.redirect('/500');
  res.status(500).render('500', {
    pageTitle: 'Server Error',
    path: '/500',
    isAuthenticated: req.session.isLoggedIn,
  });
});

mongoose
  .connect(MONGODB_URI, { useUnifiedTopology: true, useNewUrlParser: true })
  .then((result) => {
    // First arg for createServer() configures server, second is request handler, in this case, Express application
    // Commenting out because just as with request logging and asset compression, it's handled by hosting provider, and browsers don't accept custom/self-signed certificate; will be displayed as insecure with a message that connection is not private
    // https
    //   .createServer({ key: privateKey, cert: certificate }, app)
    //   .listen(process.env.PORT || 3000);
    app.listen(process.env.PORT || 3000);
  })
  .catch((err) => {
    console.log(err);
  });

这是我的邮递员请求，类似于教程视频中的请求，您可以看到我刚遇到500错误。