const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
const fs = require('fs');
const file = '../logs/mongologs'
// Connection URL
const url = 'mongodb://localhost:27017';
// Database Name
const dbName = 'MyDb';
//Mongodb connection
MongoClient.connect(url, function (err, client) {
assert.equal(null, err);
const db = client.db(dbName);
listen(db, {})
});
function listen(db, conditions) {
var filter = { ns: { $ne: 'MyDb.system.profile' } }; //filter for query
//e.g. if we need to log only insert queries, use {op:'insert'}
//e.g. if we need to log operation on only 'MyCollection' collection, use {ns: 'MyDb.MyCollection'}
//we can give a lot of filters, print and check the 'document' variable below
// set MongoDB cursor options
var cursorOptions = {
tailable: true,
awaitdata: true,
numberOfRetries: -1
};
// create stream and listen
var stream = db.collection('system.profile').find(filter, cursorOptions).stream();
// call the callback
stream.on('data', function (document) {
//this will run on every operation/query done on our database
//print 'document' to check the keys based on which we can filter
//delete data which we dont need in our log file
delete document.execStats;
delete document.keysExamined;
//-----
//-----
//append the log generated in our log file which can be tailed from command line
fs.appendFile(file, JSON.stringify(document) + '\n', function (err) {
if (err) (console.log('err'))
})
});
}