node.js - Referencing properties in mongoose

Question

I make some file.js like this:

• File Children.js

var mongoose = require('mongoose');
var ChildrentSchema = new mongoose.Schema
({
    name: String
});
module.exports = mongoose.model("Childrent", ChildrentSchema);`

• File Dad.js

var mongoose = require('mongoose');
var DadSchema = new mongoose.Schema
({
    name: String,
    child:
    {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Childrent'
    }
});
module.exports = mongoose.model("Dad", DadSchema);`

• File Grand.js

var mongoose = require('mongoose');
var GrandSchema = new mongoose.Schema
({
    name: String,
    childs:
    {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Dad'
    },
    <...>
});
module.exports = mongoose.model("Grand", GrandSchema);`

• And in file app1.js

require("./database");
var Grand = require('./Grand'),
Dad = require('./Dad'),
Childrent = require('./Childrent');
var child1 = new Childrent
({
    name: "Alex"
});
child1.save();
var dad1 = new Dad
({
    name: "Robin",
    child: child1._id
});
dad1.save();
var gran1 = new Grand
({
    name: "Paul",
    childs: dad1._id,
    <...>
})
grand1.save();`

So i need to get all grandchildrent of Paul, but i don't know how to write some code in <...>.

Somebody help me! Please!

Answer 1

这应该有效：

var gran1 = new Grand
   ({
       name: "Paul",
       childs: dad1._id,
       grandchilds: dad1.child
})