How to modulize my mongoose setup - node.js

Question

This use of db.model('Model_Name').find(...) worked before, but I've since split my database, model and controllers up, so now it seems I need to change things around Please help show where I'm going wrong:
schema.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;
var UsersSchema = new Schema({
display_name : String,
email : String
});
var ClientErrorsSchema = new Schema({
datetime : Number,
msg : String,
url : String,
line : Number
});
var users = mongoose.model('Users',UsersSchema);
var client_errors = mongoose.model('Client_Errors',ClientErrorsSchema);
module.exports = mongoose.model;
db.js
var mongoose = require('mongoose');
var model = require("./schema.js");
var MONGO = {
username: "admin",
password: "***",
server: 'localhost',
port: '*****',
db: 'db_name',
connectionString: function(){
return 'mongodb://'+this.username+':'+this.password+'#'+this.server+'/'+this.db;
},
options: {
server:{
auto_reconnect: true,
poolSize: 20,
socketOptions:{
keepAlive: 1
}
},
db: {
numberOfRetries: 10,
retryMiliSeconds: 1000
}
}
};
var db = mongoose.createConnection(MONGO.connectionString(), MONGO.options);
db.model = model;
db.on('error', function(err) {
f.consoleLogger("DB connection Error: "+err);
});
db.on('open', function() {
f.consoleLogger("DB connected");
});
db.on('close', function(str) {
f.consoleLogger("DB disconnected: "+str);
});
module.exports = db;
user.js
var db = require("./db.js");
...
db.model('Users').find(...)
So using the util.inspect, I can see the db has all of the models, but the error I'm getting on the find is TypeError: Cannot read property 'User' of undefined'.
UPDATE
Toad22222 provided great advice, and the schema appears to be valid - but the queries are not working - neither db.model.Users.find({...},function(err,data){...}); or db.model.Users.find({...}).exec(function(err,data){...}); fires the callback. I have put the same code in the on('open') event as well, nothing happens. Hopefully someone can explain why.
All advice appreciated!

Answer 1

Try out
module.exports = {
User: users,
ClientErrors: client_errors
}
instead of
module.exports = mongoose.model;
You want to be exporting the schemas you are creating, not the mongoose.model datatype.