nodejs mongodb cursor problems - node.js

Question

I have this function that I want to return the value of a mongo query but I am getting undefined values. I am attempting to read the Email address of all of the users in the users collection of my test database.
This is my code:
var mongo = require('mongodb').MongoClient;
var connectionString = "mongodb://cannotdivulge.info.com:53778/testdb";
var users;
var db = mongo.connect(connectionString, function(err, db) {
if(err)
throw err;
console.log("connected to database");
users = db.collection('users');
});
exports.findAll = function(req, res) {
var cursor = users.find();
var result;
cursor.each(function(err, doc) {
if(err)
throw err;
result = doc.Email;
});
res.send(result);
};
result should be equal to the email address but it's undefined. The value of doc.Email is not being preserved. When I place res.send() inside cursor.each(), it will return a value.
Also, I will need to use the result variable in the function before actually returning it's value. That is why I need it's value to be preserved.

Answer 1

Your findall function is async. You'll need to return the results only after completing the list. In your code, the function was returning the value of result before the first callback for each had started.
exports.findAll = function(req, res) {
var cursor = users.find();
var result = [];
cursor.each(function(err, doc) {
if(err)
throw err;
if (doc === null) {
// doc is null when the last document has been processed
res.send(result);
return;
}
// do something with each doc, like push Email into a results array
result.push(doc.Email);
});
};