File upload using Express.js (multer) is not working

Question

I'm trying to implement file upload using multer in express.js but file is not uploading in db can any one help me in this .

Here is my code:

csr.model.js

  const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const schema = new Schema({
    commonName: { type: String },
    orgName: { type: String },
    orgUnit: { type: String },
    city: { type: String },
    state: { type: String },
    country: { type: String },
    emailAdd: { type: String },
    file: { type: String },

}, { collection: 'csr' });



schema.set('toJSON', {
    virtuals: true,
    versionKey: false,
    transform: function (doc, ret) {
        delete ret._id;
        delete ret.hash;
    }
});

module.exports = mongoose.model('Csr', schema);

csr.controller.js

const express = require("express");
const router = express.Router();
const userService = require("./csr.service");
router.post("/fileupload",fileupload)

module.exports = router;

  function fileupload(req, res, next) {
    userService
  .fileupload()
  .then(() =>{
    //console.log(res);
   res.json({ success: true})})
  .catch((err) => next(err));
}

csr.service.js

 const config = require("config.json");
const jwt = require("jsonwebtoken");
const bcrypt = require("bcryptjs");
const db = require("_helpers/db");
const crypto = require("../_helpers/crypto");
// var crypto = require("crypto");
var assert = require("assert");
var ObjectId = require("mongodb").ObjectId;
const { exec } = require("child_process");
const multer = require("multer");

const Csr = db.Csr;
module.exports = {
  fileupload
};



async function fileupload() {
    var storage = multer.diskStorage({
        destination: function(req, file, cb) {
          cb(null, "uploads/");
        },
        filename: function(req, file, cb)  {
          cb(null, `${Date.now()}_${file.originalname}`);
        },
        fileFilter: function(req, file, cb)  {
          const ext = path.extname(file.originalname);
          if (ext !== ".jpg" || ext !== ".png") {
            return cb(res.status(400).end("only jpg, png are allowed"), false);
          }
          cb(null, true);
        },
      });
    
      var upload = multer({ storage: storage }).single("file");
      var csr = new Csr();
      await csr.save();
      console.log(upload)
      return upload
  }

Please suggest what is wrong in this code when I return console.log(upload) in console I got this [Function: multerMiddleware] and console.log(storage) returning like this DiskStorage { getFilename: [Function: filename], getDestination: [Function: destination] } Please some one suggest me the solution.

Thank you