node.js - 如何处理multer自定义存储中的错误？

Question

我正在使用带有锐利和自定义存储的multer，设置了图像上传并且效果很好，但是我无法正确处理错误。
当我上传例如错误的文件类型或文件太大时，服务器崩溃。

在我的app.js上

const upload = multer({
  storage: new customStorage({
    destination: function(req, file, cb) {
      cb(
        null,
        path.join(
          __dirname,
          '/images',
          new Date().toISOString().replace(/:/g, '-') +
            '-' +
            file.originalname.replace(/\s+/g, '-')
        )
      );
    }
  }),
  limits: { fileSize: 5000000 }
});

在我的customStorage.js上

const fs = require('fs');
const sharp = require('sharp');
const nodePath = require('path');

function getDestination(req, file, cb) {
  cb(null, 'images');
}

function customStorage(opts) {
  this.getDestination = opts.destination || getDestination;
}

customStorage.prototype._handleFile = function _handleFile(req, file, cb) {
  this.getDestination(req, file, function(err, path) {
    if (err) return cb(err);//***the problem is here.***

    const outStream = fs.createWriteStream(path);
    const transform = sharp().resize(200, 200);

    file.stream.pipe(transform).pipe(outStream);
    outStream.on('error', cb);
    outStream.on('finish', function() {
      cb(null, {
        path: 'images/' + nodePath.basename(path),
        size: outStream.bytesWritten
      });
    });
  });
};

customStorage.prototype._removeFile = function _removeFile(req, file, cb) {
  fs.unlink(file.path, cb);
};

module.exports = function(opts) {
  return new customStorage(opts);
};

当我上传另一个文件时，它说:

Error: Input buffer contains unsupported image format
Emitted 'error' event at:
    at sharp.pipeline (/Users/David/nodejs-app/node_modules/sharp/lib/output.js:687:18)

我想用express这样处理错误。

return res.status(422).render('admin/edit-product', {flash message here.} 

这就是我处理其他错误(例如，当字段为空时)的方式。

Answer 1

您可以将错误抛出在Multer自定义存储中(已经通过cb(err)完成)，然后将其捕获在中间件中以进行快速表达。

const upload = multer({
  storage: new customStorage({
    destination: function(req, file, cb) {
      cb(
        null,
        path.join(
          __dirname,
          '/images',
          new Date().toISOString().replace(/:/g, '-') +
            '-' +
            file.originalname.replace(/\s+/g, '-')
        )
      );
    }
  }),
  limits: { fileSize: 5000000 }
});

var uploadMiddleware = function(req, res, next){
    var handler = upload.single('media'); //use whatever makes sense here
    handler(req, res, function(err){
        //send error response if Multer threw an error
        if(err){
            res.status(500).render('admin/edit-product', "flash message here.");
        }
        //move to the next middleware, or to the route after no error was found
        next();
    });
}

然后在您的快速 route 使用uploadMiddleware:

app.post('/route/edit', uploadMiddleware, function (req, res) {
   //handle request and render normally
});