以角度5上传图像，显示500（内部服务器错误）

Question

我正在使用multer在expressjs上传图像，并且API在POSTMAN中工作正常，但每当我上传angular5中的图像以保存在mongodb时，我都会收到错误500服务器内部错误。是否有人可以建议我如何在数据库中上传图像？

// API to upload the image and working fine in POSTMAN
router.put('/users/:email', upload.single('image') , (req, res)=> {
    console.log(req.file);
    User.updateOne({email: req.params.email}, {
        $set: {
            firstName: req.body.firstName,
            lastName: req.body.lastName,
            email: req.body.email,
            password: req.body.password,
            dob: req.body.dob,
            designation: req.body.designation,
            address: req.body.address,
            mobile: req.body.mobile,
            image: req.file.path
        }
    }, 
function(err, item) {
    if(err) {
        res.json(err);
    } else {
        res.json({message: "record updated successfully!!"});
    }
}
)
});

以下是.ts文件，其中包含以下详细信息：

onFileSelected(event) {
  console.log(event);
    this.selectedFile = event.target.files[0];
  }
  // to edit the details
  updateProfile(editForm) {
     const fd = new FormData();
     fd.append('image', this.selectedFile, this.selectedFile.name);
     const newItem = {
      email: editForm.value.email,
      firstName: editForm.value.firstName,
      lastName: editForm.value.lastName,
      dob: editForm.value.dob,
      password: editForm.value.password,
      designation: editForm.value.designation,
      address: editForm.value.address,
      mobile: editForm.value.mobile,
      image: editForm.fd
    };
    this.dataService.updateUser(newItem)
    .subscribe(item => {
      console.log(item);
      this.fetchUserData();
      this.showEditForm = !this.showEditForm;

  },
  err => {
    console.log(err);
  }
);
  }