Trying to return async data in a forEach loop. Using npm async package.

queries.js

'use strict';
var async = require('async');
var Enrollment = require('../models/enrollment');
var Student = require('../models/student');
var Course = require('../models/course');

module.exports = function(app) {
  app.get('/api/studentsincourse/:courseId', function(req, res) {
    Enrollment.find({courseId: req.params.courseId}, function(err, enrollments) {
      var studentsList = [];
      async.forEach (enrollments, function(enrollee, callback) {
        console.log('Processing ', enrollee);
        Student.findOne({_id: enrollee.studentId}, function(err, students) {
          console.log(students);
          studentsList.push(students);
        });
        callback();
      });
      console.log(studentsList);
      res.send('worked')
    });
  });
};

console.log() outputs to console by the code above:

paul$ node server.js
server running on port: 3000
Processing { _id: 5460f6d9c35c21f0afbe8dd2,
studentId: '5460f5c9c35c21f0afbe8dcf',
courseId: '5460f567c35c21f0afbe8dcc',
verified: false }
Processing { _id: 5460f6f9c35c21f0afbe8dd3,
studentId: '5460f5a6c35c21f0afbe8dcd',
courseId: '5460f567c35c21f0afbe8dcc',
verified: false }
Processing { _id: 5460f70cc35c21f0afbe8dd4,
studentId: '5460f5b4c35c21f0afbe8dce',
courseId: '5460f567c35c21f0afbe8dcc',
verified: false }
[]
{ _id: 5460f5c9c35c21f0afbe8dcf, studentName: 'Gertrude' }
{ _id: 5460f5a6c35c21f0afbe8dcd, studentName: 'Fredford' }
{ _id: 5460f5b4c35c21f0afbe8dce, studentName: 'Cornelius' }

My database seed from the mongo console:

db.courses.insert({courseName: "Calculus"})
WriteResult({ "nInserted" : 1 })
db.courses.insert({courseName: "Chemistry"})
WriteResult({ "nInserted" : 1 })
db.courses.insert({courseName: "History"})
WriteResult({ "nInserted" : 1 })
db.students.insert({studentName: "Fredford"})
WriteResult({ "nInserted" : 1 })
db.students.insert({studentName: "Cornelius"})
WriteResult({ "nInserted" : 1 })
db.students.insert({studentName: "Gertrude"})
WriteResult({ "nInserted" : 1 })
db.enrollments.insert({studentId: "5460f5a6c35c21f0afbe8dcd", courseId: "5460f53cc35c21f0afbe8dca"})
WriteResult({ "nInserted" : 1 })
db.enrollments.insert({studentId: "5460f5b4c35c21f0afbe8dce", courseId: "5460f554c35c21f0afbe8dcb"})
WriteResult({ "nInserted" : 1 })
db.enrollments.insert({studentId: "5460f5c9c35c21f0afbe8dcf", courseId: "5460f567c35c21f0afbe8dcc"})
WriteResult({ "nInserted" : 1 })
db.enrollments.insert({studentId: "5460f5a6c35c21f0afbe8dcd", courseId: "5460f567c35c21f0afbe8dcc"})
WriteResult({ "nInserted" : 1 })
db.enrollments.insert({studentId: "5460f5b4c35c21f0afbe8dce", courseId: "5460f567c35c21f0afbe8dcc"})
WriteResult({ "nInserted" : 1 })