Exposing Mongoose missing ID on save bug

no_id.js

var mongoose = require('mongoose');
var eyes = require('eyes');


mongoose.connect('mongodb://localhost/null_id');


// schema definition
var A = new mongoose.Schema({
    f1: String,
    f2: [ {
        type: Number,
        index: true
    } ],
    b: {
        type: mongoose.Schema.ObjectId,
        ref: B
    }
});

var B = new mongoose.Schema({
    f1: String,
    f2: [ {
        type: Number,
        index: true
    } ]
});


// models
var models = {
    A: mongoose.model('A', A),
    B: mongoose.model('B', B)
};

// triggers
A.pre('save', connectB);

function connectB(next) {
    console.log('connectB');

    var newA = this;
    var query = models.B.find({}).where('not.gonna', 'happen');

    function queryResult(err, docs) {
        console.log('queryResult');

        if (docs.length < 1) {
            // always true due to query which will not give any results
            createB(bCreated);
        }
    }

    function createB(callback) {
        console.log('createB');

        var b = new models.B({
            f1: 'b',
            f2: [ 0, 1, 2 ]
        });
        b.save(callback);
    }

    function bCreated(err) {
        console.log('bCreated');

        eyes.inspect(this.id, 'this id');
        eyes.inspect(this, 'this');
        console.log(this.emitted.complete[0]._id); // <-- this works, but shouldn't it be 'this.id'? this seems like fiddling with internals...

        newA.b = this; // this will fail

        next(null);
    }

    query.exec(queryResult);
}


function main() {
    console.log('main');

    var a = new models.A({
        f1: 'a',
        f2: [ 0, 1, 2 ]
    });

    function aSaved(err) {
        console.log('aSaved');
    }

    a.save(aSaved);
}

main();

Simpler version, exposing same error, here: https://gist.github.com/1631992