Save file in an array using gridfs-stream

My web app allows the user to create a word document, then this document is saved in a collection called 'Files' using grid-stream. 'Files' is structured the following way:

Files:

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

var FileSchema = new Schema({
   userID:{type: String},
   //names:{type: String},
   file:[{type: Schema.Types.Mixed}]
},{collection: 'Files'});
module.exports = mongoose.model('Files', FileSchema);

Everytime the user saves the word document, I want to save it in the array, this is because the user can have more the one word document.

Here is my save method:

 var Files = require('C:/Users/mississauga/OneDrive/workspace/Editor/Models/files.js');
var mongoose = require('mongoose');
var User = require('C:/Users/mississauga/OneDrive/workspace/Editor/Models/users.js');
var db = mongoose.connection;
db.safe = {w: 1};
//var GridStore = mongoose.mongo.GridStore;
var Grid = require ('gridfs-stream');
var mongo = mongoose.mongo;
var gfs = new Grid(db, mongo);
//var fs = require ('fs');

var SaveFile = function(req, names, contents, userid){
    console.log("inside SaveFile");
    console.log("this is the name: " + names);
    console.log("this is the content: " + contents);
    //console.log(" the user: " + req.session.user);
    //var gs = new GridStore (db, names, "w",gsOptions);
    console.log("The username : " + userid);

Files.findOne({'userID' :  userid },
    function(err, user) {
            // In case of any error, return using the done 
            //method
            if (err){
                console.log('Error in Finding user: '+err);
                return done(err);
            }
            // already exists
            if (user) {
                console.log("inside user");
                Files.findOne({'file': {'name':names}},
                    function(err, filename){
                        if(filename){
                            console.log("file already Exists");
                        }
                        else{
                            var writeStream = req.pipe(gfs.createWriteStream({
                                filename: names,

                            }));
                            console.log("Passed writestrea");

                            writeStream.on('close', function(){
                                return res.status(200).send({
                                    message:'Success'
                                });
                            });
                            writeStream.write(contents);
                            writeStream.end();
                            user.save(function(err) {
                                console.log("found user");
                                if (err){
                                    console.log('Error in Saving file:'+err);  
                                    throw err;  
                                }
                                console.log('File Saved');    
                                return filename;
                            });
                        }
                    }


                 );
            }
            else {
                console.log("inside else");

                var writeStream = gfs.createWriteStream({
                    filename: names,

                });

                console.log("Passed writestrea");

                writeStream.on('close', function(){
                    return res.status(200).send({
                        message:'Success'
                    });
                });
                req.pipe(writeStream);
                writeStream.write(contents);
                writeStream.end();

                var newFile = new Files();  
                newFile.userID= userid;
                writeStream.on('close', function(file){
                    newFile.file = file;
                });


                newFile.save(function(err) {
                    console.log("found user");
                    if (err){
                        console.log('Error in Saving file:'+err);  
                        throw err;  
                    }
                    console.log('File Saved');    
                    return filename;
                });

            }
    });


   console.log("passed Grid");
  }
module.exports = SaveFile;

When I run the code the file is not saved, this is what I see in the database:

How do I save the file to the array?