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Friend Request System - Express, MongoDB, EJS

I want to create a social network thus allowing users to send and interact with frind requests. As of now I have created the register, log-in and "search for other users function".
When I find and select another user, I display their user-info and have created a "Add friend" button.
Can anyone help me in a direction of the creation of the "Add friend" option? I have looked around for some time now, and not been able to find the correct solution. Below I have attached my UserSchema and route for finding users:
//User Schema
const UserSchema = new mongoose.Schema({
firstName: {
type: String,
required: true
},
lastName: {
type: String,
required: true
},
password: {
type: String,
required: true
},
},{ collection: 'Users' });
//Get single user based on ID
router.get('/user/get:id', ensureAuthenticated, function (req, res) {
MongoClient.connect(DBUri,{useUnifiedTopology: true }, function (err, db) {
let dbo = db.db(DBName);
const query = {_id: objectId(req.params.id)}
dbo.collection("Users").find(query).toArray(function(err, resultTasks) {
if (err) throw err;
res.render('../View/findFriend', {
resultTasks: resultTasks
});
db.close();
});
});
});

You can add something like this in your user schema:
friends: [{ type : ObjectId, ref: 'User' }],
OR
friends: userSchema
Take the one which suits you.
What that will do is add an array to the user, Then you can store IDs of friends.(Who are other users, hence the ref: 'User')
Then, When you have to fetch users you can do:
User.find(<ID or whatever you have to find Users>).populate('friends')
Also, To push a new friend simply use: user.friends.push(newFriend._id)

mongoose extract nested arrays from multiple objects into one array

const userSchema = new Schema(
{
_id: Schema.Types.ObjectId,
name: String,
posts: [{ type: Schema.Types.ObjectId, ref: "Post" }],
following: [{ type: Schema.Types.ObjectId, ref: "User" }]
}
};
I want to extract all the posts from all the Users in the 'following' array, put them into one single array, sort them and then display the first 20. I was wondering if that is possible within the cursor or if I have to load it into memory.
function createFeed(user) {
User.findOne({ name: user })
.populate({
path: "following",
populate: {
path: "posts"
}
})
//put all the posts into one array
.sort(...) //sort by time created
.limit(...) //only get the newest n posts
.exec((err, result) => {
if (err) console.log("error", err);
console.log("result", //sorted tweets array);
});
};
(I don't want to filter all the posts in my 'Posts' collection to check if they are made by the user since that would be a lot more expensive)

You can use distinct query in mongoDB
db.User.distinct('following',{})

If you are trying to filter your populate with a condition, then you should be doing this:
User.findOne({ name: user })
.populate({
path: 'posts',
match: { user: 'XXX' }
})
Even more better would be to query the posts with the user filter condition and then populate user details.

mongoose document filtering properties

I have defined a schema like
var UserSchema = new Schema({
firstName: { type: String, required: true },
lastName: { type: String, required: true },
email: { type: String, required: true },
location: { type: String, required: true },
picture: { type: String, required: true },
passwordHash: { type: String, required: true },
resetPasswordToken: String,
resetPasswordExpired: Boolean
});
I have a REST Endpoint which return list of all users. In that list I want to hide some properties i.e, passwordHash, resetPasswordToken, resetPasswordExpired
I defined a custom filter function like below
var doFilterUser = function(user) {
_.omit(user, ['passwordHash', 'resetPasswordToken', 'resetPasswordExpired']);
user.id = user._id;
delete user._id;
delete user.__v;
return user;
};
_ is lodash
When I check my API is responding with all user properties
This filter function is defined in common helper module and I am calling it like
User.findOne({_id: id}, function(err, user) {
var filtered = helper.doFilterUser(user);
});
How to resolve this issue?

Try this:
You are allowed to access certain values through mongoose.
User.findOne({_id: id}, 'firstName lastName email location picture', function(err, user){
console.log(user);
});
You just mention the fields needed, after the query.
Hope it helps....

The problem here is that you still have a mongoose document that conforms to s strict schema. If you want to change that document, then you need to make it a "raw" object without all the additional controls:
User.findOne({_id: id}, function(err, user) {
var filtered = helper.doFilterUser(user.toObject());
});
So the .toObject() method here will return an object in it's raw form. That allows you to manipulate the keys how you wish.

You can also explicitly direct it not to serve back certain properties. Useful if you don't want to render a hashed password over the wire. The find method would look like this:
User.find({}, '-id -__v',function(err,users){
})
or
User.findOne({_id: id}, '-id -__v',function(err,user){
})

Mongoose request for id field returns id and _id

In my Mongoose schema I have an id field which has a unique ID for each document. This runs off the same system used by the default _id field like so:
var JobSchema = new mongoose.Schema({
id: { type:String, required:true, unique:true, index:true, default:mongoose.Types.ObjectId },
title: { type: String },
brief: { type: String }
});
module.exports = mongoose.model("Job", JobSchema);
Now, if I query the schema to get id and title I'd do it like this:
Job.find().select("id title").exec(function(err, jobs) {
if (err) throw err;
res.send(jobs);
});
However, I've found this returns id and title as expected, but it also return the default _id field. Why is that and how do I stop it?

Inside the find() function you can pass two parameters (criteria and projection). Projection are the fields that you want (or not). In your case you can change your code to
Job.find({}, {_id:0, id: 1, title: 1}, function(err, jobs) {
if (err) throw err;
res.send(jobs);
});
and it should do it.

There is an option to prevent the id on schema level.
For me this worked perfectly fine.
new Schema({ name: String }, { id: false });
Mongoose Docs

Multiple populates - mongoosejs

Just a simple query, for example with a double ref in the model.
Schema / Model
var OrderSchema = new Schema({
user: {
type : Schema.Types.ObjectId,
ref : 'User',
required: true
},
meal: {
type : Schema.Types.ObjectId,
ref : 'Meal',
required: true
},
});
var OrderModel = db.model('Order', OrderSchema);
Query
OrderModel.find()
.populate('user') // works
.populate('meal') // dont works
.exec(function (err, results) {
// callback
});
I already tried something like
.populate('user meal')
.populate(['user', 'meal'])
In fact only one of the populates works.
So, how do is get two populates working ?

You're already using the correct syntax of:
OrderModel.find()
.populate('user')
.populate('meal')
.exec(function (err, results) {
// callback
});
Perhaps the meal ObjectId from the order isn't in the Meals collection?

UPDATE:
This solution remains for the version 3.x of Mongoose http://mongoosejs.com/docs/3.8.x/docs/populate.html but is no longer documented for >= 4.x versions of Mongoose and so the answer from #JohnnyHK is the only valid one for now on.
ORIGINAL POST
If you're using Mongoose >= 3.6, you can pass a space delimited string of the path names to populate:
OrderModel.find()
.populate('user meal')
.exec(function (err, results) {
// callback
});
http://mongoosejs.com/docs/populate.html

This has probably been resolved already, but this is my take on multiple & deep population in Mongodb > 3.6:
OrderModel.find().populate([{
path: 'user',
model: 'User'
}, {
path: 'meal',
model: 'Meal'
}]).exec(function(err, order) {
if(err) throw err;
if(order) {
// execute on order
console.log(order.user.username); // prints user's username
console.log(order.meal.value); // you get the idea
}
});
There are probably other ways to do this, but this makes very readable code for beginners (like me)

The best solution in my opinion is arrays when you are populating more than one foreign field on the same level. My code shows that I have multiple populates for different levels.
const patients = await Patient.find({})
.populate([{
path: 'files',
populate: {
path: 'authorizations',
model: 'Authorization'
},
populate: {
path: 'claims',
model: 'Claim',
options: {
sort: { startDate: 1 }
}
}
}, {
path: 'policies',
model: 'Policy',
populate: {
path: 'vobs',
populate: [{
path: 'benefits'
}, {
path: 'eligibility',
model: 'Eligibility'
}]
}
}]);
As you can see, wherever I needed more than one field of a document populated, I encased the populate key in an array and provided an array of objects, each object having a different path. Most robust and concise way to do it, in my opinion.

You can use array syntax:
let results = await OrderModel.find().populate(['user', 'meal']);
You can also select which properties you want from each populate:
let results = await OrderModel.find().populate([{path: 'user', select: 'firstname'}, {path: 'meal', select: 'name'}]);

Latest mongoose v5.9.15
has ability to take array of populate fields
so you can do,
.populate([ 'field1', 'field2' ])

You can try:
OrderModel.find()
.populate('user')
.populate('meal')
.exec(function (err, results) {
// callback
});
or with array options
OrderModel.find()
.populate([
{
path: "path1",
select: "field",
model: Model1
},
{
path: "path2",
select: "field2",
model: Model2
}
])
.exec(function (err, results) {
// callback
});

In model file do something like:-
doctorid:{
type:Schema.Types.ObjectId, ref:'doctor'
},
clinicid:{
type:Schema.Types.ObjectId, ref:'baseClinic'
}
In js file for adding operator use Something like:-
const clinicObj = await BaseClinic.findOne({clinicId:req.body.clinicid})
const doctorObj = await Doctor.findOne({ doctorId : req.body.doctorid}) ;
**and add data as:-**
const newOperator = new Operator({
clinicid:clinicObj._id,
doctorid: doctorObj._id
});
Now, while populating
apiRoutes.post("/operator-by-id", async (req, res) => {
const id = req.body.id;
const isExist = await Operator.find({ _id: id }).populate(['doctorid','clinicid'])
if (isExist.length > 0) {
res.send(isExist)
} else {
res.send("No operator found");
}
});

i have same problem , but my mistake not in populate , i have an error in Model
if you do this
uncorrected
user: {
type: [Schema.Types.ObjectId],
ref: 'User'
}
correct
user: [{
type: Schema.Types.ObjectId,
ref: 'User'
}]
you must put array around of object like this

To populate multiple fields with array of objects in controller/action function, model of both is already referred in schema of post
post.find({}).populate('user').populate('comments').exec(function (err,posts)
{
if(err)
{
console.log("error in post");
}
return res.render('home',{
h1:"home Page",
posts:posts,
});
});

I think you are trying to the nested population you can visit official docs
User.
findOne({ name: 'Val' }).
populate({
path: 'friends',
// Get friends of friends - populate the 'friends' array for every friend
populate: { path: 'friends' }
});