node.js - express3-handlebars and mongoose

i'm stuck on what i know is probably a super easy issue for more experienced node.js developers to solve. i can't seem to get my returned query to display in my handlebars template.

i have my app setup like so:

app.js

var express  = require('express')
  , mongoose = require('mongoose')
  , exphbs   = require('express3-handlebars');

var uri = 'mongodb://localhost/test';

global.db = mongoose.connect(uri);

var app = express();

// configure Express
app.configure(function() {
  app.set('views', __dirname + '/views');
  app.set('view engine', 'handlebars'); //set to handlebars to use the handlebars engine
  app.engine('handlebars', exphbs({defaultLayout: 'main'})); //set to express3-handlebars to use handlebars
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use('/', express.static('public'));
  app.use(app.router);
});

var api = require('./public/js/api');

app.get('/', function (req, res) {
    res.render('home', {user: api.user});
});

app.listen(3000);

console.log('Listening on port 3000');

I then have my schema in a model folder and it is named userschema.js

userschema.js

var Schema = require('mongoose').Schema;

//create our user model
var userSchema = Schema({
  username: { type: String, required: true, unique: true },
  email: { type: String, required: true, unique: true },
  password: { type: String, required: true},
});

// db is global
module.exports = db.model('users', userSchema);

i am then exposing the model through a js file called api.js

var model = require('../../models/userschema')

exports.modelName = function (req, res) {
  res.send('my model name is ' + model.modelName);
}

exports.user = function(req, res) {
    model.findOne({username: 'TestUser'}, function (err, user) {
        //res.send(user);
        res.render('home', {user: user.username});
        console.log('USER:' + user.username);
  });
}

i don't understand why i can't get this to display on my handlebars template. if i change api.user to 'ME' then i see output, if i don't i get an error. also if i go app.get('/', api.user); i see my query returned. any suggestions would be appreciated.