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

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