Getting error while creating session using Mongoose and node.js - node.js

Question

I am trying to manage the transnational data using mongoose and node.js but while creating session its throwing the following error.
Error:
TypeError: session.startTransaction is not a function
at DemoProjectService.transferBalance (/home/anil/Desktop/subhrajyoti/project/demo1/service/account.service.js:32:21)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:189:7)
The below is my service where I am trying to create the session.
async transferBalance(req,res) {
let conn = null;
try{
conn = await connectMasterDb();
if(_.isNull(conn)) {
return false;
}
let from = req.body.from;
let to = req.body.to;
let amount = req.body.amount;
const customerCollection = loadMongoModel('Account');
const session = conn.startSession();
session.startTransaction();
const opts = { session, new: true };
const A = await customerCollection.findOneAndUpdate({ name: from }, { $inc: { balance: -amount } }, opts);
if (A.balance < 0) {
// If A would have negative balance, fail and abort the transaction
// `session.abortTransaction()` will undo the above `findOneAndUpdate()`
throw new Error('Insufficient funds: ' + (A.balance + amount));
}
const B = await customerCollection.findOneAndUpdate({ name: to }, { $inc: { balance: amount } }, opts);
await session.commitTransaction();
session.endSession();
conn.disconnect();
if (_.isEmpty(A) && _.isEmpty(B)) {
return [];
}else{
return { from: A, to: B };
}
}catch(error) {
console.log(error);
return false;
}
}
I am explaining my mongodb connection code file below.
const Mongoose = require('mongoose').Mongoose,
fs = require('fs'),
{ ObjectID } = require('mongodb');
class DemoProjectMongo {
async _connect() {
this.dbInstance = null;
const mongooseInstance = new Mongoose();
const mongodebug = false;
const url = `mongodb://admin:admin#localhost:27017/practice`;
const options = {
useNewUrlParser: true,
useCreateIndex: true,
connectTimeoutMS: 5000000,
poolSize: 10000,
useUnifiedTopology: true,
// autoIndex: false
};
this.dbInstance = await mongooseInstance.connect(url, options);
mongooseInstance.set('bufferCommands', false);
mongooseInstance.set('useFindAndModify', false);
if(mongodebug === true) {
mongooseInstance.set('debug', true);
}
return this.dbInstance;
}
async connectMasterDb() {
return await this. _connect();
}
collection(collectionName) {
try{
const path_name = '/home/anil/Desktop/subhrajyoti/project/demo1/model';
const model = `${path_name}/${collectionName}.model.js`;
if (fs.existsSync(model)) {
let SchemaModel = require(model);
return this.dbInstance.model(collectionName, SchemaModel);
}
}catch(error) {
console.log(error);
}
}
isObjectID(value) {
let response = value;
if (_.isArray(response)) {
response = _.map(response, res => {
if (ObjectID.isValid(res)) {
return new ObjectID(res);
}
return res;
});
} else if (ObjectID.isValid(response)) {
response = new ObjectID(response);
}
return response;
}
}
const edQartMongoUtil = new DemoProjectMongo();
module.exports = {
loadMongoModel: edQartMongoUtil.collection.bind(edQartMongoUtil),
connectMasterDb: edQartMongoUtil.connectMasterDb.bind(edQartMongoUtil),
isObjectID: edQartMongoUtil.isObjectID.bind(edQartMongoUtil)
}
Here I want to manage some transitional record but getting the above error. Can anybody help me to resolve this error.