Mongoose not returning document from mongo - node.js

Question

I am trying to get Mongoose to query my mongo instance for a specific document (using the _id attribute). I currently have the following route:
router.get('/document/', function (req, res) {
var getDocuments = function (callback) {
var options = { server: { socketOptions: { keepAlive: 1000 } } };
var connectionString = 'mongodb://user:password#server:27017/db';
var pID = req.query.id;
pID = pID.trim();
console.log(pID);
var documentArray = [];
// Connected handler
Mongoose.connect(connectionString, function (err) {
var db = Mongoose.connection.useDb('db');
var pCollection = db.collection("collection");
//grab all items from pCollection
pCollection.find({ '_id': pID }, function (error, pDocument) {
if (error) {
console.log(error);
}
if (pDocument) {
// res.send(JSON.stringify(pDocument));
console.log(pDocument);
}
else {
console.log("nothing");
}
});
db.close();
});
};
getDocuments(function () {
});
});
The result returned is not a json document and does not seem to return a usable value. What am I doing wrong? Thanks for any help in advance!
EDIT:
I went back and changed the route to the following:
router.get('/document/', function (req, res) {
var pID = req.query.id;
pID = pID.trim();
console.log(pID);
Document.findById(pID, function (error, document) {
if (error) {
console.log(error);
}
else {
console.log(document);
}
});
});
I also created the following model:
var mongoose = require('mongoose');
var DocumentSchema = require('../schemas/documents');
var Document = mongoose.model('documents', DocumentSchema, 'Documents');
module.exports = Document;
And used the following schema:
var mongoose = require('mongoose');
var DocumentSchema = new mongoose.Schema({
documenttPK: String,
locationID: String,
docName: String,
SerialNumber: String,
documentID: String,
dateEntered: Date,
activeFlag: Boolean
});
module.exports = DocumentSchema;
My app.js makes a single call to a db file:
var mongoose = require('mongoose');
mongoose.connect('mongodb://user:password#server:27017/db');
But the result is still null. Is something wrong with the above code?