mongodb node.js client, connect hangs
javascript, mongodb, node.js
Solution
It's been a long time since this question has been asked, but I'll post an answer for those wishing to use `mongodb` as opposed to `mongoose` or `mongojs` (at the time of this writing mongojs depends on an older insecure version of the mongodb driver).
TL;DR Version
The program executes normally, but adding the line `db.close();` will allow your program to terminate normally:
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect(
'mongodb://my.mongo.db.server.ip:27017/test',
function(err, db) {
if(err) throw err;
console.log("shows during connect call back");
db.close(); //call this when you are done.
});
Why Node Appears to Hang When Using `mongodb.connect()`
As explained in this answer, node will not exit when it has a callback waiting for an event.
In this case, `connect()` registers a callback that waits for the event `'close'` to be emitted, indicating that all database connections have been closed. This is why unless you call `db.close()`, your script will appear to hang. Note however, everything you code will execute, your program will just not terminate normally.
An Example
To demonstrate, if you put the following code block into a file called `connect.js`...
const MongoClient = require('mongodb').MongoClient;
async function dbconnect() {
console.log("This will print.");
const db = await MongoClient.connect(
'mongodb://my.mongo.db.server.ip:27017/test');
console.log("This will print too!");
And execute it within a terminal...
$ node connect.js
the result will be:
$ node connect.js
This will print.
This will print too!
You will get no further command line prompts.
In conclusion remember to close your database connections, and all will be well in the world!
Problem
node-mongodb-native node.js client hangs when `MongoClient.connect(...)`, but `mongodb-client (shell command line)` works on terminal. Any clues? ``` var MongoClient = require('mongodb').MongoClient; MongoClient.connect( 'mongodb://my.mongo.db.server.ip:27017/test', function(err, db) { if(err) throw err; console.log("shows during connect call back"); }); // When load into node shell, it hangs forever ```