javascript - What is the right way to make a synchronous MongoDB query in Node.js?

Question

I'm using the Node.JS driver for MongoDB, and I'd like to perform a synchronous query, like such:

function getAThing()
{
    var db = new mongo.Db("mydatabase", server, {});

    db.open(function(err, db)
    {
        db.authenticate("myuser", "mypassword", function(err, success)
        {
            if (success)
            {
                db.collection("Things", function(err, collection)
                {
                    collection.findOne({ name : "bob"}, function(err, thing)
                    {                           
                        return thing;
                    });
                });
            }
        });
    });
}

The problem is, db.open is an asychronous call (it doesn't block), so the getAThing returns "undefined" and I want it to return the results of the query. I'm sure I could some sort of blocking mechanism, but I'd like to know the right way to do something like this.

Answer 1

ES 6 (Node 8+)

You can utilize async/await

await operator pauses the execution of asynchronous function until the Promise is resolved and returns the value.

This way your code will work in synchronous way:

const query = MySchema.findOne({ name: /tester/gi });
const userData = await query.exec();
console.log(userData)

---

Older Solution - June 2013 ;)

Now the Mongo Sync is available, this is the right way to make a synchronous MongoDB query in Node.js.

I am using this for the same. You can just write sync method like below:

var Server = require("mongo-sync").Server;
var server = new Server('127.0.0.1');
var result = server.db("testdb").getCollection("testCollection").find().toArray();
console.log(result);

Note: Its dependent on the node-fiber and some issues are there with it on windows 8.

Happy coding :)