MongoDB vanishes attributes on save - node.js

Question

Hi im using MongoDB + Mongoose and some strange magic happens in my app.
Ive defined my Schema as
var schema = mongoose.Schema({
username: {type: mongoose.Schema.ObjectId, ref: 'Profile' , required:true},
user: {type: mongoose.Schema.ObjectId, ref: 'Profile' , required:true},
message: String
});
As I save my Document the new entry has ben saved and stored. It has a message and a ref on Profile in username but the user field is missing.
Same happens if I rename it to userId :/ Registered a pre save listener : already missing in my callback before save
There is no Error and I do not know how to handle this situation. Please help. Would call the a team but I can not afford
Edit :
Full Schema
var mongoose = require('mongoose');
var schema = mongoose.Schema({
username: {type: mongoose.Schema.ObjectId, ref: 'Profile' , required:true},
user: {type: mongoose.Schema.ObjectId, ref: 'Profile' , required:true},
message: String
});
var autoPopulate = function(next) {
this.populate('user');
this.populate('username');
next();
};
var autoReduce = function(next) {
if(this.username){
this.username = this.username._id;
}
if(this.user){
this.user= this.user._id;
}
next();
};
schema.
pre('findOne', autoPopulate).
pre('find', autoPopulate).
pre('save', autoReduce);
module.exports = mongoose.model('News',schema);
Request Body
{
"message": "Hi",
"username": {
"_id": "5a736607bee0360014fb28e6",
"name": "Juventus Florin"
},
"user": {
"_id": "5a736607bee0360014fb28e6",
"name": "Juventus Florin"
}
}
Code
app.put("/api/news", function(request, response) {
response.header("Content-Type", "application/json");
var payload = request.body;
new News(payload).save(function(err) {
if(err){
response.status(500).send({"message": "This is an error!", "error":err, "payload":payload});
}else{
response.status(200).send(payload);
}
});
});
After saving there is an new entry , looks like (username is populated)
{
"message": "Hi",
"username": {
"_id": "5a736607bee0360014fb28e6",
"name": "Juventus Florin"
},
"_id":"5a736607bee0360014fb278h"
}

Answer 1

Solution :
On 1 to 1 references there is no need to
this.user = this.user._id;
Only on 1 to Many references. Removed the pre save listener autoReduce and it works