selecting data from several collections after finding the proper id in documents - node.js

Question

I have an almost working solution, but I believe my solution is bad programmed and I don't know how to make it better. Maybe it should be done with mongoose population, but I can't figure out how it works and how to adjust my code.
I have 2 collections: author and books. They are imported from MySQL with data - so I can't change the structure.
author:
{ "_id" : ObjectId("59492addd80eb0f9c1b42fd9"), "id_a" : 1, "name" : "Agatha Christie", "gender" : "female", "born" : 1890, "birthplace" : "England", "genre" : "crime"
}
{ "_id" : ObjectId("594935e1d80eb0f9c1b42fdb"), "id_a" : 2, "name" : "Stephen King", "gender" : "male", "born" : 1947, "birthplace" : "U.S.", "genre" : "horror" }
books:
{ "_id" : ObjectId("59492cd1d80eb0f9c1b42fda"), "id_b" : 1, "title" : "Murder on the Orient Express", "id_a" : 1, "pub_date" : 1934, "publisher" : "Collins Crime Club",
"pages" : 256, "description" : "Hercule Poirot, the internationally famous detective, boards the Orient Express (Simplon-Orient-Express) in Istanbul. The train is unus
ually crowded for the time of year. Poirot secures a berth only with the help of his friend Monsieur Bouc, a director of the Compagnie Internationale des Wagons-Lits. W
hen a Mr. Harris fails to show up, Poirot takes his place. On the second night, Poirot gets a compartment to himself..." }
{ "_id" : ObjectId("59493779d80eb0f9c1b42fdc"), "id_b" : 2, "title" : "The A.B.C. Murders", "id_a" : 1, "pub_date" : 1936, "publisher" : "Collins Crime Club", "pages" :
256, "description" : "The novel follows the eponymous murders and their investigation as seen by Arthur Hastings, Poirot's old friend. Poirot receives typed letters si
gned by A.B.C. In each is given the date and location of the next murder. A.B.C. moves alphabetically: Alice Ascher is a tobacco shop owner killed in her shop in Andove
r, Betty Barnard is a flirty waitress killed in Bexhill, and Sir Carmichael Clarke is a wealthy man killed at his home in Churston..." }
{ "_id" : ObjectId("59493858d80eb0f9c1b42fdd"), "id_b" : 3, "title" : "The Shining", "id_a" : 2, "pub_date" : 1977, "publisher" : "Doubleday", "pages" : 447, "descripti
on" : "The Shining mainly takes place in the fictional Overlook Hotel, an isolated, haunted resort located in the Colorado Rockies. The history of the hotel, which is d
escribed in backstory by several characters, includes the deaths of some of its guests and of former winter caretaker Delbert Grady, who succumbed to cabin fever and ki
lled his family and himself..." }
I want to find with author's name his id in the collection author and use his id to find all his books in the collection books. But the json-result should be a combination of selected field from both collections. For example I search for Agatha Christie and want get following selected fields as one json-object (name and genger from author + title and description from books as one object) Desired Api result in postman:
[ {
"name": "Agatha Christie",
"gender": "femail",
"title" : "Murder on the Orient Express",
"description" : "Hercule Poirot, the internationally famous detective, boards the Orient Express (Simplon-Orient-Express) in Istanbul...."
},
{
"name": "Agatha Christie",
"gender": "femail",
"title" : "The A.B.C. Murders",
"description" : "The novel follows the eponymous murders and their investigation as seen by Arthur Hastings, Poirot's old friend..."
}]
here is my code:
api.js
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
mongoose.connect('mongodb://localhost/books');
var db = mongoose.connection;
db.on('connected', function() {
console.log('MongoDB connection successful');
});
Author = require('./models/books');
Book = require('./models/books');
app.post('/api/Books', function(req, res){
Author.getAuthor({name : req.body.name}, 10, function(err, data){
if (err){
throw err;
}
var tmp = data[0].id_a;
Book.getBook({id_a : tmp}, 10, function(err, data2){
if (err){
throw err;
}
var result = [data, data2];
console.log(result);
res.json(result);
});
});
});
app.listen(3000);
console.log('server started and waits on port 3000');
books.js
var mongoose = require('mongoose');
var authorSchema = mongoose.Schema({
id_a:{
type: Number,
required: true
},
name:{
type: String,
required: true
},
gender:{
type: String,
required: true
},
born:{
type: Number,
required: true
},
birthplace:{
type: String,
required: true
},
genre:{
type: String,
required: true
}},
{ collection: 'author'}
);
var booksSchema = mongoose.Schema({
id_b:{
type: Number,
required: true
},
title:{
type: String,
required: true
},
id_a:{
type: Number,
required: true
},
pub_date:{
type: Number,
required: true
},
publisher:{
type: String,
required: true
},
pages:{
type: Number,
required: true
},
description:{
type: String,
required: true
}},
{ collection: 'books'}
);
var Author = module.exports = mongoose.model('author', authorSchema);
var Book = module.exports = mongoose.model('books', booksSchema);
module.exports.getAuthor = function(query, limit, callback){
Author.find(query, {'_id': 0}).select('id_a').limit(limit).exec(callback);
}
module.exports.getBook = function(query, limit, callback){
Book.find(query).select('-_id id_a title').limit(limit).exec(callback);
}
With my app I can find the proper books to particular author, but my result is without author's name and gender - I don't know how to do it. Also I make a request with nested functions - there might be much better solution for it. My solution feels very dirty. How can I improve my code and get data from both collections? A working adjusted example would be realy great!

Answer 1

First you have to add those changes:
model:
var booksSchema = mongoose.Schema({
...
},
{ collection: 'books', toJSON: { virtuals: true } })
// Foreign keys definitions
// http://mongoosejs.com/docs/populate.html#populate-virtuals
booksSchema.virtual('author', {
ref: 'author',
localField: 'id_a',
foreignField: 'id_a',
justOne: true // for many-to-1 relationships
});
module.exports.getAuthor = function (query) {
return Author.findOne(query).exec();
}
// this help you get books with author
module.exports.getBook = function (query) {
return Book.find(query)
.populate('author')
.exec();
}
app code:
app.post('/api/Books', function (req, res) {
Author.getAuthor({ name: req.body.name }, 10)
.then(author => {
return Book.getBook({ id_a: author.id_a });
})
.then(result => {
console.log(result);
res.json(result);
})
.catch(error => {
// TODO:
});
});
result should be:
[{...book info,...author info }]
I hope this help you