Followers / Following structure in MongoDB - node.js

Question

My website has a 'follow' feature, where users can follow each other.
Ideally, a user1 would be able to follow a user2, and have their _id present inside user2.followers, aswell as user2 should be present in user1.following.
My first thought was to simply do something like
/*
UserSchema = new Schema({
username: String,
followers: [
{
type: Schema.Types.ObjectId,
ref: 'user'
}
],
following: [
{
type: Schema.Types.ObjectId,
ref: 'user'
}
]
})
*/
// POST /api/users/follow
let user = await User.findById(userId)
let follow = await User.findById(followId)
if (!user || !follow) {
return errorHandle()
}
user.following.push(follow._id);
follow.followers.push(user._id);
user.save();
follow.save();
/*
User.findById(userId)
.populate('following', 'username')
.then(user => console.log(user.following))
*/
But these would be difficult to scale and maintain (as well as other problems).
So I want to hear from you, the stack community, what a proper way to deal with this system be, as I am new to MongoDB and Databases as a whole.
Any help is appreciated

Answer 1

hey I was getting the same problem I figured it out how it can be done. I have two way of writing the code choose as per your choice.
UserSchema
var UserSchema = new Schema({
name:{
type:String,
required:true
},
email:{
type:String,
required:true
},
password:{
type:String,
required:true
},
following: [
{
user:{
type: Schema.ObjectId,
ref: 'User'
},
}
],
followers: [
{
user:{
type: Schema.ObjectId,
ref: 'User'
},
}
],
date:{
type:Date,
default: Date.now
},
});
First Method
User.js
You can use .then and .catch method
router.post("/user/:user_id/follow-user", (req,res) => {
// finding user by id (to whom user is going to follow)
User.findById(req.params.user_id)
.then(user => {
//check if follow reqest by user2 is already exist in user1 followers
if(user.followers.filter(follower => follower.user.toString()=== req.user._id).length > 0 ){
return res.status(400).json({ alreadyLike : "User already like the post"})
}
// the requested user will push and save to followers of other user to whom request has made
user.followers.push(req.user._id);
var followedUser = user._id;
user.save()
// we will find current user by email you can find it by _id also
User.findOne({ email: req.user.email })
.then(user => {
// now push the user to following of its own and save the user
user.following.push(followedUser);
user.save().then(user => res.json(user))
})
.catch(err => console.log("error cant follow again you jave already followed the user"))
})
})
second method
Normal method by call backs
router.post("/user/:user_id/follow-user", (req,res) => {
// finding user by id (to whom user is going to follow)
User.findById(req.params.user_id, function(err, user) {
// the requested user will push and save to followers of other user to whom request has made
user.followers.push(req.user._id);
var followedUser = user._id;
user.save(function(err){
if(err){
console.log(err)
}
else
{
// Secondly, find the user account for the logged in user
User.findOne({ email: req.user.email }, function(err, user) {
user.following.push(followedUser);
user.save(function(err){
if(err){
console.log(err)
}
else{
//send success response
res.json(user)
}
});
});
}
});
});
});