How to get into another collections with forigen keys - node.js

Question

I have these collections (books,book_genres,genres,books)
my book Schema is like that
var bookModel = function () {
var bookSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
author_id: {
type: mongoose.Schema.Types.ObjectId,
ref: "Author",
},
title: String,
description: String,
cover: String,
likes: Number,
});
return mongoose.model("Book", bookSchema);
};
module.exports = new bookModel();
I'm using dust templating and I'm rendering that collection data on my layout like that
{#books}
<div class="large-4 small-12 columns book">
<div class="row img-row">
<img src="{.cover}" alt="">
</div>
<div class="row">
<h3 class="small-12">{.title}</h3>
<h4 class="small-5 columns ">{.author_id}</h4>
<h4 class="small-7 columns ">{.name}</h4>
</div>
<div class="row p-row">
<p class="small-12">{.description}</p>
</div>
</div>
{/books}
my author Schema is like that
var authorModel = function () {
var authorSchema = mongoose.Schema({
_id: mongoose.Schema.Types.ObjectId,
name: String,
});
return mongoose.model("Author", authorSchema);
};
I want to be able to reach to author name so I can render it on my layout through the author_id that I'm getting from the book Schema (for sure the id in the authors collection is the same as the author_id in the books collection)
I tried to search for some solutions but no one was using dust templating so I wasn't able to figure that out

Answer 1

You can use populate to resolve the Author reference:
bookModel.find({}).populate('author_id').exec();
You should then be able to access the referenced user fields with:
<h4 class="small-7 columns ">{.author_id.name}</h4>
In your case, you should change your code to:
module.exports = function (router) {
router.get('/', function (req, res) {
Book.find({})
.populate('author_id')
.exec(function (err, books) {
if (err) {
console.log(err);
}
var model = { books: books };
res.render('index', model);
});
});
};