Read result from an exported function callback

Question

Read result from an exported function callback

I can't find a solution to this simple issue: I want to call a function exported from an external .js and save the output. I've done the following:

db.js

function findMessages () {
    allMsg = mongoose.model('allMsg');
    allMsg.find(function (err, message) {
       console.log('here is ok');
       return message;
    });
};

exports.returnMessages = findMessages;

app.js

var db = require( './db' );

app.get('/message', function(req, res){
  var messages = db.returnMessages();
  console.log('Nothing here (undefined): ' + messages);
});

How can I read messages in app.js? Thanks.

node.js
callback
mongoose

Answer 1

Simple answer: You cannot. That's not how callbacks work.

You need to change findMessages() to accept a callback function.

function findMessages (callback) {
    allMsg = mongoose.model('allMsg');
    allMsg.find(function (err, message) {
       callback(message)
    });
};

// app.js
app.get('/message', function(req, res) {
    db.returnMessages(function(messages) {
        console.log(messages);
    });
});