TypeError：在Heroku上部署后无法读取未定义的属性'path'

Question

我正在使用multer-storage-cloudinary上载图像，然后获取cloudinary生成的图像URL，该URL将保存到mongoDB Cloud Service中。我试过在本地主机上运行，​​并且工作正常。但是，部署到heroku之后，运行命令heroku logs --tail

时会收到这些消息

2020-10-15T06:20:08.110693+00:00 app[web.1]: (node:23) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'path' of undefined

这是我的代码：

控制器

async (req, res, _next) => {
await Models.Users.user_detail.create(
  {
    gender: req.body.gender,
    birth_date: req.body.birth_date,
    image_URL: req.file.path,
    created_at: moment(),
    user_id: req.body.user_id,
  },
  (err) => {
    if (err) {
      res.json(SERVER_ERROR(err));
    } else {
      res.json(OK("data successfully added"));
    }
  }
)

路线

router.post(
"/detail/create",
multer({ storage: Storage.storageConfig }).single("image_URL"),
UserDetail.create)

存储配置

new CloudinaryStorage({
    cloudinary: cloudinary.v2,
    params: {
      folder: async (req, file) => "user",
    },
  })

Cloudinary配置

import cloudinary from "cloudinary"

cloudinary.v2.config({
  cloud_name: global.env.CLOUDINARY_NAME,
  api_key: global.env.CLOUDINARY_API_KEY,
  api_secret: global.env.CLOUDINARY_API_SECRET,
})
export default cloudinary

谁能解释我为什么？谢谢！