How to run node js mongdb operation synchronously - node.js

Question

I have following code, I need to wait till mongodb operation completed.
const nativeClient = require("mongodb").MongoClient;
async function ingestData() {
var data = [
{name: "a", address: "a_add"},
{name: "b", address: "b_add"}
];
console.log(" start ingestData");
await insertPersons(data);
console.log("end ingestData");
}
async function insertPersons(data) {
nativeClient.connect("mongodb://localhost:27017", function(err, client) {
if (err) throw err;
var db = client.db("testdb");
db.collection("person")
.insertMany(data)
.then(function(res) {
console.log(`Number of rec inserted: ${res.insertedCount}`);
return true;
})
.catch(function(err) {
console.log(`Failed to persist ${data.length} rec in db: ${err}`);
return false;
});
});
}
ingestData();
Current Output
start ingestData
end ingestData
Number of rec inserted: 2
Expected output
start ingestData
Number of rec inserted: 2
end ingestData

Answer 1

You are using async/await incorrectly.
If you use await, the called function must return a promise, so there is something to wait for.
If you are not using await anywhere in a function, that function does not need to be marked as async.
You're not doing either of these things.
You can return a promise that resolves when the work is done:
function insertPersons(data) {
return nativeClient.connect("mongodb://localhost:27017").then(client => {
return client.db("testdb").collection("person").insertMany(data).then(res => {
console.log(`Number of rec inserted: ${res.insertedCount}`);
return true;
});
}).catch(function(err) {
console.log(`Failed to persist ${data.length} rec in db: ${err}`);
return false;
});
}
or you can use await to wait until the work is done.
async function insertPersons(data) {
try {
let client = await nativeClient.connect("mongodb://localhost:27017"):
let db = client.db("testdb");
let res = await db.collection("person").insertMany(data);
console.log(`Number of rec inserted: ${res.insertedCount}`);
return true;
} catch (err) {
console.log(`Failed to persist ${data.length} rec in db: ${err}`);
return false;
}
}