Mongoose callback hangs node js

Question

I'm new to mongoose and javascript in general, and want to connect to a locally running mongodb. The following code give no errors, will perform all of the console logs except for the one inside the db.on('connected', function() call. The console log before that prints out a 1, and I can see on my mongodb terminal that a connection is being accepted. What am I missing here?

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/rawStockData');

https.get(requestURL, function(res) {
  var data = '';
  res.on('data', function (chunk) {
    data += chunk
  });
  res.on('end', function() {
    var jsonObj = JSON.parse(data);
    console.log('Data Parsed');

    var db = mongoose.connection;
    db.on('error', console.error.bind(console, 'connection error:'));
    console.log(db.readyState);
    db.on('connected', function() {
      console.log('ConnectedToDatabase!');
    });
  });
});

What are you trying to achieve here? Mongoose will queue any query until it's connected so you shouldn't need to do any of this in your request handler. — JohnnyHK
– JohnnyHK, Commented Feb 22, 2018 at 13:59
I'm trying to get historic stock data through the API and put it in the mongodb. My thinking was, due to the asynchronous nature of javascript, I need to make sure I'm connected before I tried to save the data. Is this unnecessary? — Adam Kall
– Adam Kall, Commented Feb 22, 2018 at 14:12
Yeah, it's unnecessary with Mongoose as it already waits until the connection is established before saving. — JohnnyHK
– JohnnyHK, Commented Feb 22, 2018 at 14:20

semanser · Accepted Answer · 2018-02-22 13:48:52Z

2

In your case mongoose.connect is called before the event listeners are installed.

You attach the event listener for open at a much later point in time (when a request is being handled).

Try to edit your code and put the event listeners just after the connect function.

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/rawStockData');


var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.on('connected', function() {
   console.log('ConnectedToDatabase!');
});

https.get(requestURL, function(res) {
  var data = '';
  res.on('data', function (chunk) {
    data += chunk
  });
  res.on('end', function() {
    var jsonObj = JSON.parse(data);
    console.log('Data Parsed');
  });
});

answered Feb 22, 2018 at 13:48

semanser

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2 Comments

Adam Kall Over a year ago

This fixed it! Thank you!

Adam Kall Over a year ago

I did, but I have less than 15 reputation so it isn't shown publicly

Sparw · Accepted Answer · 2018-02-22 13:48:13Z

0

I think you just have to replace your

db.on('connected', ..)

to

db.once('connected', ..)

You can also have something like this :

mongoose.connection.once('connected', function(err) {
    if (err) {
        console.log(err);
    }
    else {
        console.log("Connected to Database");
    }
}).on('error', function (err) {
    console.log(err);
}).on('disconnected', function () {
    console.log('Disconnected to database');
});

Hope it helps.

answered Feb 22, 2018 at 13:48

Sparw

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1 Comment

Adam Kall Over a year ago

This did not solve the problem. Nothing about the behavior in the original post has changed, but thank for you trying to help!

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