Develop Reference

how to populate following documents

I have two mongoose db schemas as follows
Posts schema
return model('post',
Schema({
title: {
type: String,
required: true
},
content: {
type: String,
required: true
},
createdBy: {
type: Types.ObjectId,
ref:"user"
},
},
{ timestamps: true })
);
Like schema
return model('like',
Schema({
userId: {
type: Types.ObjectId,
required: true,
ref: "user"
},
postId: {
type: Types.ObjectId,
required: true,
ref: "post"
}
},
{ timestamps: true })
);
how to populate like documents with post documents?i also want to consider the case where a post not have a like schema at all.

Mongoose: Check if value exists in string array

I am querying to get all articles that have a specific source name and category.
I have an article schema that looks like below.
The issue I'm facing is that, it fetches the articles with the correct source name, but it doesn't fetch for the right category. For example, if source is "cnn" and category is "sports", it fetches all articles from CNN correctly, but not with correct categories (the articles may have a categories of ['politics', 'culture'] with no sports)
const article_schema = new mongoose.Schema({
title: {
type: String,
required: true
},
thumbnail_url: {
type: String,
required: true
},
summary: {
type: String,
required: true
},
text: {
type: String,
required: true
},
link: {
type: String,
required: true
},
publish_date: {
type: String,
required: true
},
source: {
name: {
type: String,
required: true
},
name_slug: {
type: String,
required: true
},
link: {
type: String,
required: true
},
display_picture_url: {
type: String,
required: true
},
biography: {
type: String,
required: true
},
tags: {
type: [String],
required: true
},
rssFeeds: [{
url: {
type: String,
required: true
},
categories: {
type: [String],
required: true
}
}]
}
});
let getNews = async (req, res) => {
const { sort, filter, current_page, limit, category_slug } = req.body;
let articles = await Article.findOne({ 'source.name_slug': filter, categories: category_slug });
res.setHeader('Content-Type', 'application/json');
res.status(200).send({ articles });
}

Node Populate Array with object reference

I need to Populate courses of StudentSchema with the courses (Object_id) from CoursesSchema that belong to the major same as students major
let StudentSchema = new Schema({
_id: new Schema.Types.ObjectId,
emplId: {
type: Number,
required: true
},
major:{
type: String,
required: true
},
courses:[{
type: mongoose.Schema.Types.ObjectId,
ref: 'courses',
grade:{
type: String,
required: false,
}
}],
});
const courseSchema = new mongoose.Schema({
code: {
type: String,
required: true
},
title: {
type: String,
required: true
},
//array of majors that a courses is required for e.g: ['CS', 'CIS']
major: {
type: Array,
required: false,
},
//
CIS:{
type: Boolean,
required: false,
},
CNT:{
type: Boolean,
required: false,
},
CS:{
type: Boolean,
required: false,
},
GIS:{
type: Boolean,
required: false,
},
})
What do I do?
StudentCoursesRouter.get('/studentcourses', (req, res) => {
Courses.find({CS: true}, (err, courses) => {
if ( err ) {
console.log('Error occured while getting records');
res.json(err);
} else {
courseMap = {}
courses.forEach(function(course) {
courseMap[course._id] = course._id;
});
//res.send(courses);
Students.find({empleId: 12345678}).courses.push(courses);
}
res.json(Students);
})
This is what i am doing but it is not populating courses of student and gives an empty array for courses.
API Request Response Screenshot

You mention populate but you are not using populate?
e.g. Students.find({empleId: 12345678}).populate('course')
If you want it lean u also need to install mongoose-lean-virtuals
e.g. Students.find({empleId: 12345678}).populate('course').lean({ virtuals: true })

What is the best way to attach properties to mongoose documents

I have an array of posts and each post contains an author id. I want to loop through each post and find author from User model by using author id and then attach it to post. What is the best and efficient way to do it. I am currently doing it this way, but it decreases the performance. Thanks.
posts = await Promise.all(
posts.map(async post => {
post.author = await User.findById(post.author).lean();
return post;
})
);
// POST SCHEMA
const postSchema = new mongoose.Schema({
author: {
type: String,
required: true
},
body: {
type: String,
required: true
},
post_image: {
url: String,
public_id: String,
width: Number,
height: Number
},
date_created: {
type: Date,
default: Date.now()
}
});
// USER SCHEMA
const userSchema = new mongoose.Schema({
name: {
type: String,
required: true
},
email: {
type: String,
required: true,
unique: true
},
password: {
type: String,
required: true
},
register_date: {
type: Date,
required: true,
default: Date.now()
},
friends: {
type: Array,
default: []
}
});

// NEW POST SCHEMA
const postSchema = new mongoose.Schema({
author: {
type: mongoose.Schema.Types.ObjectId,
ref: 'users',
required: true
},
body: {
type: String,
required: true
},
post_image: {
url: String,
public_id: String,
width: Number,
height: Number
},
date_created: {
type: Date,
default: Date.now()
}
});
// USER SCHEMA
const userSchema = new mongoose.Schema({
name: {
type: String,
required: true
},
email: {
type: String,
required: true,
unique: true
},
password: {
type: String,
required: true
},
register_date: {
type: Date,
required: true,
default: Date.now()
},
friends: [{
type: mongoose.Schema.Types.ObjectId,
ref: 'users',
required: true
}],
});
You can use auto population of mongo object in mongoose. It won't cause performance issues as it uses id index. Similar to this doc: https://mongoosejs.com/docs/populate.html
Your query will look like this:
const post = await Post.find({ author: { $in: req.user.friends }})
.populate('author')
.exec();
console.log(post);
Or you can use aggregate according to this document: https://mongoosejs.com/docs/api/aggregate.html
Your query will then look like:
const query = [
{ $match: { author: { $in: req.user.friends } } },
{ $lookup: { from: "users", localField: "author", foreignField: "_id", as: "authorDetails" } },
{ $unwind: "authorDetails" },
]
const post = await Post.aggregate(query).exec();
console.log(post);

What's the difference between document.property and document.get('property')?

I have a mongoose document that has timestamps option enabled. I want to make decisions based on this timestamps but I noticed something weird according to my understanding.
I tried to get those values the traditional way (document.createdAt) but that returns undefined. But if I use document.get('createdAt') the value comes as in the database. The docs don't say anything about this. My question is: ¿Why timestamps behave this way?
Edit
The schema I'm using has an array of embedded schemas:
const Customer = new mongoose.Schema({
roles: {
type: [{
type: String,
enum: 'app b2b iot'.split(' '),
}],
default: 'app',
set: (value = []) => (value.includes('app')
? value
: value.concat('app')),
},
email: {
address: {
type: String,
trim: true,
lowercase: true,
set(email) {
this._previousEmail = this.email.address
return email
},
},
verified: {
type: Boolean,
},
token: String,
},
nickname: {
type: String,
trim: true,
},
recoveryToken: String,
gender: String,
birthday: String,
lastLogin: Date,
isAnonymous: {
type: Boolean,
default: false,
},
devices: [Device],
});
Device schema:
const Device = new mongoose.Schema({
customer: {
type: ObjectId,
ref: 'Customer',
required: true,
},
handle: {
type: String,
},
platform: {
type: String,
required: true,
set: toLowerCase,
},
info: Mixed,
smartFilterTags: [{
type: String,
}],
paidUntil: Date,
nh: {
tier: String,
_id: {
type: ObjectId,
},
location: {
type: {
type: String,
enum: ['Point'],
default: 'Point',
},
coordinates: [{
type: Number,
}],
},
})
I have a base plugin that apply when I compile models:
function basePlugin(schema) {
schema.add({
archivedAt: Date,
})
schema.set('timestamps', true)
schema.set('toJSON', {
virtuals: true,
})
schema.set('toObject', {
virtuals: true,
})
}