Synchroneous call with mongodbnative

Question

I have the following problem with mongodb-native. I have a function whose purpose is to return some element from db.

function get(){
  db.collection('test').findOne({...},{...},function(err, doc){
     // my doc is here
  });
  // but here my doc is undefined
  // so I can not return it

  return doc;
}

So due to asynchroneous nature of node, I can not get my doc back. So how can I make it synchroneous (or is there any other way)?

I need for my single page app. So when my client does some action, ajax request is sent which is handled by get function. This function has to send back JSON.

Answer 1

The answer is to have your code work asynchroneous, that is the whole concept of JavaScript.

Thus if you have something like this in your synchroneous program:

function get() {
  db.collection('test').findOne({...},{...},function(err,doc) {
  });
  return doc;
}

var doc = get();
console.log(doc);

You can refactor it into:

function printToConsole(err, doc) {
    console.log(doc);
}
function get(callback) {
    db.collection('test').findOne({...},{...},callback);
}
get(printToConsole);

It is not a unique solution, there are other workflows. Some like promises will make your code flatter.

But my personal suggestion, is to initially learn how to code asynchroneous code without supporting libraries. Initially it feels like a pain, just give it some time and you will start enjoying the idea.