gfs is undefined

[SUMANTH-hyphen]

I'm trying to connect to the database and declare the gfs variable in one file and share it to another file where I want to fetch the file details

mongo.connection.js

const mongoose = require("mongoose");
const Grid = require("gridfs-stream");

let gfs;

const establishConnection = async () => {
  try {
    mongoose.set("strictQuery", false);
    await mongoose.connect(process.env.DB_URI, {
      useNewUrlParser: true,
      useUnifiedTopology: true,
    });
    const connect = mongoose.connection;

    connect.on("error", (err) => {
      console.error("Mongoose connection error:", err);
    });

    connect.once("open", () => {
      gfs = new mongoose.mongo.GridFSBucket(connect.db, { bucketName: "uploads" });
      console.log("Mongoose connection successful.");
    });
  } catch (err) {
    console.error("Mongoose connection error:", err);
    throw err;
  }
};

const getGfsInstance = () => {
  if (!gfs) {
    throw new Error("Connection not established. Call establishConnection first.");
  }
  return gfs;
};

module.exports = { establishConnection, getGfsInstance };

user.controller.js

const { gfs } = require("../connnection/mongo.connection");

exports.postRetriveAll = async (res, req) => {
  try {
    // await establishConnection();

    console.log("Retrieved gfs:", gfs);

    // Retrieve all file details from the "uploads" bucket
    gfs.find({}).toArray((err, files) => {
      if (err) {
        console.error("Error:", err);
      } else {
        console.log("Files:", files);
      }
    });
  } 
  catch (err) {
    console.log(err);
    return err;
  }
};

Output

Mongoose connection successful.
Retrieved gfs: undefined
TypeError: Cannot read properties of undefined (reading 'find')

i have called establishConnection() function in app.js file initially and also called it once again in user.controller.js but it didn't worked i also used the promise method but it didn't work