Express 从控制器获取multerS3密钥

我正在使用multer在AmazonS3中存储文件。我需要从控制器模块获取文件的multerS3密钥，以便以后访问。我的路线模块：

var express = require('express');
var router = express.Router();
var post_controller = require('../controllers/postController')
var aws = require('aws-sdk');
var multer = require('multer');
var multerS3 = require('multer-s3');
var mongoose = require('mongoose');
const s3 = new aws.S3();
const upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: 'compressor-input',
    metadata: function(req, file, cb) {
      cb(null, {fieldName: file.fieldname});
    },
    key: function (req, file, cb) {
      cb(null, mongoose.Types.ObjectId())
    }
  })
});

router.post('/:id/upload', upload.array('item_images', 12), post_controller.images_upload);

---

MulterS3不公开任何特定于文件的参数。您应该在控制器中使用S3.putObject（），并在传递给router.post函数的中间件或控制器模块中生成密钥。Express fileupload在使用S3.putObject（）时非常有用，因为它公开了Express request对象中的文件，如：

req.files

req.files将包含有关Amazon返回的上传文件的所有信息

app.post('/upload', upload.array('photos', 3), function(req, res, next) {
  
  console.log(req.files)
  
  res.send('Successfully uploaded ' + req.files.length + ' files!')
})