mongo_read_preffered_Test.js

const { MongoClient } = require("mongodb");
var ReadPreference = require('mongodb').ReadPreference

// Replace the following with your MongoDB deployment's connection
// string.
const uri =
  "mongodb://prmongotest:XSXz98HsbkOGyQN1SNnjilJKf5eDWDMXpJIvus8441jiiROq1WO86P84enVHw2izDtRTVndUev2l6hDX4VW6Tw==@prmongotest.mongo.cosmos.azure.com:10255/?ssl=true&replicaSet=globaldb&retrywrites=false&maxIdleTimeMS=120000&appName=@prmongotest@";
const client = new MongoClient(uri, { monitorCommands:true });
// Replace <event name> with the name of the event you are subscribing to.
const eventName = "commandStarted";
client.on(eventName, event => {
  // console.log(`received ${eventName}: ${JSON.stringify(event, null, 2)}`);

  if(event.command.hasOwnProperty("find"))
    console.log(JSON.stringify(event));

});
async function run() {
  try {
    await client.connect();
    // Establish and verify connection
    const findResult = await client.db("scheduler").collection("dataplane",{readPreference: ReadPreference.SECONDARY_PREFERRED}).find({}).toArray();
    // console.log('Found documents =>', findResult);

    // console.log("Connected successfully");
  } finally {
    // Ensures that the client will close when you finish/error
    await client.close();
  }


}

// run().catch(console.dir);

setInterval(function(){ 
  run().catch(console.dir);
}, 10000);