CODEWITHSUNDEEP
javascriptnode.js
Joseph
Joseph

Reputation: 23

Return value to variable from function

I am looking to return a value to a varible when I call the function in nodejs.
The output I am looking for is "Calling From Glasgow to Euston"
The output I am getting is "Calling From undefined to undefined"

Code is the following.

function trainstation(stx, callBack) {
  MongoClient.connect(ttdb, function(err, db) {
  if (err) throw err;
   var dbo = db.db("ttdb");
   var collection = dbo.collection("tlc");
   var find = collection.find( { "Stanox" : stx } );
   find.toArray(function(err, result) {
     if (err) throw err;
    db.close();
    return callBack(result);        
   });
 });
};

function gettrain(){
   var ts1 = trainstation(9531, function(x){
     return x[0]['Station Name'];
   });
   var ts2 = trainstation(31033, function(x){
   return x[0]['Station Name'];
   });
   console.log("Calling From", ts1, "to", ts2);
  };
gettrain();

Thanks :)

Upvotes: 0

Views: 50

Answers (1)

jarmod
jarmod

Reputation: 78883

I don't use the MongoDB package and I don't have MongoDB up & running right now to test this, so I've written this code purely based on a quick read of the reference documentation. Perhaps you can test this and we'll fix any minor issues. Copy this code to a new source file and test it.

What I've done is to take advantage of the MongoDB package's promise features. You can see that the code is more linear and simpler to follow.

const MongoClient = require('mongodb').MongoClient;
const ttdb = 'mongodb://localhost:27017'; // or your DB URL

const trainstation = async (Stanox) => {
  const client = MongoClient(ttdb);
  await client.connect();
  const dbo = client.db("ttdb");
  const collection = dbo.collection("tlc");
  const result = await collection.find({Stanox}).toArray();
  client.close();
  return result;       
};

const gettrain = async () => {
  const ts1 = await trainstation(9531);
  const ts2 = await trainstation(31033);
  const sn1 = ts1[0]['Station Name'];
  const sn2 = ts2[0]['Station Name'];
  console.log("Calling From", sn1, "to", sn2);
};

gettrain();

Upvotes: 3

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