MongoDb transactions done right and DB connections V5

[axmad22]

When using the feathers CLI it generates a mongodb.js file, the mongodbClient is stored in app and used when setting up mongoDb services. My question is when I use app.get('mongodbClient') do I need to close the client connections, also I could not use it to startSession ...so I added dbClient is this a good thing and do i need to terminate connection after using it.

/// mongodb.js
import {MongoClient} from 'mongodb'

export const mongodb = app => {
    const connection = app.get('mongodb')
    const database = new URL(connection).pathname.substring(1)
    //added this so I can use the Session in transactions
    const mongoClient = MongoClient.connect(connection).then((client) => client) 
   // cant I use this instead for transactions 
    const mongoDbClient = MongoClient.connect(connection).then((client) => client.db(database)) 

   // when using these do I need to close the connection after using them 
    app.set('dbClient', mongoClient)  //added this too
    app.set('mongodbClient', mongoDbClient)
}

/// Method using Transaction in some service
async foo() {
   const client = await this.app.get('dbClient')
   const session = client.startSession()
   try {
        await session.withTransaction(async () => {
             // do some work
        })
    } finally {
        await session.endSession()
        await client.close()  // do i need to close connection
    }
}

In the service.class.js files the getOptions method calls app.get('mongodbClient') is this the only place in feathers where they are used and do connection need to be closed after.....am confused am getting the feeling that multiple connection are made to the database and left open.. Thank you