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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)

How to use a mongoose model in another model?

I have the two following models. In the user model I want to use an array of Requests and in Request Model I want to use User as an attribute(without the password). How can I do it?
var userSchema = new Schema({
cartaoCidadao: {
type: String,
required: true,
index: {
unique: true,
},
match: /[0-9]{8}/,
},
password: { type: String, required: true },
role: { type: String },
estado: { type: String, enum: ["Infetado", "Suspeito"] },
});
var requestSchema = new Schema({
encaminhado: { type: String },
pessoaRisco: { type: String },
trabalhoRisco: { type: String },
estadoPedido: { type: String },
resultado: { type: String },
});

You can use the schema you defined as a type itself:
var userSchema = new Schema({
// ...
requests: {
type: [requestSchema] // this property type is: array of requests
}
// ...
});
If both models are stored in database and you probably want to go for their association. You can reference one model from another. (see the answer of Muhammad Lahin)
Then you query your parent model and associate the children models with it (https://mongoosejs.com/docs/populate.html)
And here is an example of how you can exclude some fields during the population:
https://mongoosejs.com/docs/populate.html#query-conditions
It will be something like:
User.
find(/* some query */).
populate({
path: 'requests',
select: 'fieldToSelect1 fieldToSelect2' // You can control which fields to include
}).
exec();

you can do something like this
var userSchema = new Schema({
requests: [
{
type: Schema.Types.ObjectId,
ref: "Request",
}
]
});
var requestSchema = new Schema({
user: {
type: Schema.Types.ObjectId,
ref: "User"
}
})

you can set the type of the user in the request model like this
type: schema.Types.ObjectID,
ref: 'users'
which users id schema of users and when you want to send the whole user data in the response, use populate and in populate you can omit the password too
now if you see the mondodb database in the request database the whole user object is not saved and only the user_id is saved so you dont have access to the user. you have to send another request to get the user data from the gived user_id which is not good. the solution is you set the schema as I said and when you are sending a response which have the data of the request use populate to add the userdata to the response
res.json({request: requests.find(//options to find a specified request).populate('users','name')})
first argument is the model which is users and the second argument is the wanted field of the users model for example this will return the name of the user. you can add more arguments to add all of them except the password

const mongoose = require('mongoose')
const productSchema = new mongoose.Schema({
user: {
type: mongoose.Types.ObjectId,
ref: 'User'
}
});

Mongoose deleteMany subdocuments and related subdocuments

I have a document Project with an array of subdocuments, with a schema Tasks. Tasks has an array of subdocuments with a schema Comments.
const projectSchema = new Schema({
_id: Schema.Types.ObjectId,
name: { type: String, required: true, unique: true },
description: { type: String, default: '' },
tasks: [{ type: Schema.Types.ObjectId, ref: 'Threads' }]
});
module.exports = mongoose.model('Project', projectSchema);
const tasksSchema = new Schema({
projectId: { type: Schema.Types.ObjectId },
_id: Schema.Types.ObjectId,
title: { type: String, required: true },
text: { type: String, required: true },
comments: [{ type: Schema.Types.ObjectId, ref: 'Replies' }]
})
module.exports = mongoose.model('Tasks', tasksSchema);
const commentSchema = new Schema({
taskId: { type: Schema.Types.ObjectId },
_id: Schema.Types.ObjectId,
text: { type: String, required: true }
})
module.exports = mongoose.model('Comment', commentSchema);
When I delete the Project document I want to delete every Task and every Comment relate to that project.
To delete the Project I use findOneAndDelete so I set up a post middleware to delete all the Tasks
projectSchema.post('findOneAndDelete', function(doc, next) {
mongoose.model('Tasks').deleteMany({ projectId: doc._id }).exec();
next();
})
But now I don’t know how to delete every comment, because deletemany returns an object with the result of the operation.
Should I map the array of Tasks and call findOneAndDelete every time and then delete every single comment? It looks very inefficient for a lot of tasks.

How about embedding comments in post? since its one to many(not huge) relation. So in your code where you delete a project, you first delete all posts, which contain all the comments, only after it succeeds you delete the project. It will also benefit your read performance significantly because you just have to return a single post document instead of multiple(1post + many comment) documents.
Embedding post to project could also be possible, but depending on the size and number of possible posts, its probably better to keep it as a separate document.
In this case you need some logic to ensure consistency.
Here you could use mongodb's new feature, transaction. But I think for this case a transaction is not necessary.(Also I find it quite unstable for now) You could go with the "eventual consistency" method.
Basically you just delete all the posts related to a project and then delete a project. And then you run batches to check for any inconsistency.(check if there are any posts where its project doesnt exist. If it doestnt then delete the posts)

Load only required plugin into the Schema when saving a model

Plugins is quite a powerful feature in Mongoose.js, but there is one thing I have got stuck with. I need to load only the required plugin into the Schema when saving a model. Because If I don't do it, the other unnecessary plugins are loaded automatically along with lots of validation errors.
Here is my schema
// models/user_collection.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var UserSchema = new Schema({
username: { type: String, required: true },
password: { type: String, required: true },
role: String // either 'memeber' or 'admin'
});
// Member User Plugin
UserSchema.plugin(function (schema) {
schema.add({
locality: { type: String, required: true },
contactNo: { type: Number, min: 13, max: 13 }
});
});
// Admin User Plugin
UserSchema.plugin(function (schema) {
schema.add({
accountNo: { type: String, required: true },
settingsArray: Array
});
});
mongoose.model('User', UserSchema);
Now whenever I try to save a record only for member user, the Schema automatically loads the Admin plugin, responding with validation errors.
So,
var member = new User();
member.username = 'XYZ';
member.password = createHash('ABC') // a hashing method;
member.role = 'member';
member.locality = 'USA';
member.contactNo = 123456;
member.save(function(err, user) {
if(err) { console.log(err); res.send(err); return; }
// if successful I do my stuff
});
As soon as the save method is executed, I get validation errors from Admin like
"accountNo is required", ( I am not gonna paste the stack trace here, it will get messy, but you got the point )
Now I know that it is not an issue or bug with Mongoose.js, but I am doing something wrong here. Can you guys please guide me how to do it correctly ?

The thing is you are applying both the plugins to the same schema. So all the plugin functionality is being added to the schema. So accountNo and locality is required. Plugins are used to define common code at one place and use it across different schemas.
The way you have used plugins here, you just have broken down the definition of the model to smaller parts. You could as well put everything under the schema and would have gotten the same effect.
Read about plugins again.
As you said, I guess Discriminators is the way to go.

Mongodb data structure on posts, comments, save and likes

I am just learning how to build websites using MEANJS, and I am structuring my data but unsure on the best practice, I am very new to the NoSql concept.
I need to store:
questions
answers
likes
saved_questions
In my app I enable the user to save questions to be viewed later, as well as they can access any answer they posted. And I provide some stats for each question (i.e. number of likes, number of answers, etc)
Should I create one document for "question" and everything inside of it:
{_id: <ObjectId>,
user_id: <ObjectId>,
question: 'how can we....',
answers: [{user_id: <ObjectId>, answer: ''}],
likes: [{user_id: <ObjectId>}],
saves: [{user_id: <ObjectId>}]
}
Or should I make multiple documents for each? Or should I use both methods?

I would have at least two database models, maybe one for the User and the other for the Question. One of the great things about the MEAN.JS boiler plate is that it already comes with a User module complete with sign-up, login/logout functionality. So you have that out of the way as soon as you deploy your new project.
With that already out of the way, I would use the Yo Generator to create a new CRUD module called Question. You can add the files manually, but Yo helps you do it quickly and accurately by automatically placing the files in the correct place, complete with sample code to help you set it up. To learn how to use the Yo Generator I would look at the Yo Generator Section of the MEAN.JS docs.
From your app's root directory, run yo meanjs:crud-module Question. This will create all of the necessary files you need for the database model, as well as a new module on the front & back ends with samples of how to create/read/update/delete the questions. Now, if you log in, you will see the new module in your menu bar.
Then open app/controllers/models/question.server.model.js. This is the file that you can define your new database model. Depending on how complex/relational you want the data to be, you'd want your Mongoose model to look something like this:
var QuestionSchema = new Schema({
created: {
type: Date,
default: Date.now
},
title: {
type: String,
default: '',
trim: true,
required: 'Title cannot be blank'
},
question: {
type: String,
default: '',
trim: true
},
user: {
type: Schema.ObjectId,
ref: 'User'
},
answers: {
type: Array,
default: []
},
likes: {
type: Array,
default: []
},
saves: {
type: Array,
default: []
}
});
Obviously this is very simplified. You may want to create separate mongoose models for the likes, saves, and reports so you can store more data about each (ie: user_id, date, reason for reporting/saving/liking, etc.) To read more about how to make the perfect mongoose model for your needs, I would definitely check out the docs about Mongoose Schemas at mongoosejs.com.
I hope that helps!
Continued...
To get a list of a given user's actions, I would go ahead and make a new Mongoose Schema for each type of action (comments, likes, saves), and store the details of user's actions there. For instance, in Answers schema you could store the actual comment, who said it, when they said it, what question it was for etc. Then simply query the action tables for a given user ID to retrieve your list of actions.
So..
var QuestionSchema = new Schema({
created: {
type: Date,
default: Date.now
},
title: {
type: String,
default: '',
trim: true,
required: 'Title cannot be blank'
},
question: {
type: String,
default: '',
trim: true
},
user: {
type: Schema.ObjectId,
ref: 'User'
}
});
var AnswerSchema = new Schema({
created: {
type: Date,
default: Date.now
},
question: {
type: Schema.ObjectId,
ref: 'Question'
},
user: {
type: Schema.ObjectId,
ref: 'User'
},
answer: {
type: String,
default: '',
trim: true
}
});