How to Install and Connect MongoDB to our Next.js Project

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1.Connect To MongoDB

• First we should install mongoose package from npm then we should make utils function to connect file to db

export default async function connectToDb() {
  try {
    if (mongoose.connections[0].readyState) {
      //true is once is already Connected
      return false;
    }
    await mongoose.connect("mongodb://127.0.0.1/my_database");
    console.log("Connected Successfully");
  } catch (error) {}
}

• then for use in function handler we should import our connectToDb and use in first line of handler

import connectToDb from "db.js";
async function handler(req, res) {
  if (req.method !== "GET") {
    return false;
  }
  connectToDb();
}

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Create Schema

• Schema is a blueprint of our data , the algorithm to how our data Object should be Created for models we create folder call models models/userModel.js

const schema = mongoose.Schema({
  username: {
    type: String,
    required: true,
  },
  email: {
    required: true,
    type: String,
  },
  password: {
    required: true,
    type: String,
    minLength: 8,
  },
});
// Capital&unplural
const usersModel = mongoose.models.User || mongoose.model("User", schema);
//if exist dont make it twice
export default usersModel;

• in our project every time we want to access to userModel we just import that
• in this example we create every single js file for each models moongose.model() (remmeber don`t add "s" at the end of the files => mongo in create models already add "s" at the end")

Mongoose automatically looks for the plural version of your model name. For example, if you use const MyModel = mongoose.model('Ticket', mySchema); Then MyModel will use the tickets collection, not the ticket collection. For more details read the model docs.

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1.Create Data in model (POST Request)

• for make first data fill in model first we export userModel which that was const usersModel = mongoose.model("User", schema);

  we import that in main function

  then say :

  import userModel from "path";
  // for post and create and insert into model
  const user = await userModel.create({ username, email, password });
  if (user) {
    return res.status(201).json({ message: "create user successfuly", user });
  } else {
    return res.status(400).json({ message: "invalid user data" });
  }

---

2.Get all collections data (GET request)

for receive All data in user collection for EX:

import userModel from "path";
const users = await userModel.find();
return res.status(200).json({ message: "Get All users successfuly", users });

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3.get Single object from all collections data (single GET request)

• for catch one single object from model: notice for dev this function handler api we need dynamic path also cause we get id from req.query

[id].js

in handler function we get this params from: req.query

import userModel from "path";
const user = await userModel.findOne({ _id: req.query });

• you can also do this with find method find vs findOne if we search for 2 for example username find return array of object with all same searchs but findOne returns first object that find so for this case it's better to use findOne method

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4.delete an item from all collections data (DELETE request)

for delete one single item from data base model.findOneAndDelete()

import userModel from "path";

const user = await userModel.findOneAndDelete({ _id: req.query });

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5.update an item from all collections data (PUT request)

for delete one single item from data base model.findOneAndUpdate()

import userModel from "path";

const user = await userModel.findOneAndUpdate(
  { _id: req.query },
  { username, email, password }
);

---

validate user ObjectID

import { isValidObjectId } from "mongoose";

if (!isValidObjectId(req.query)) {
  const user = await userModel.findOneAndDelete({ _id: req.query });
}
```### How to use this collections in SSR & SSG

```javascript
import connectToDb from "path";
import usersModel from "path";
export async function getStaticProps() {
  connectToDb();
  const users = await usersModel.find();
  return {
    props: {
      users: JSON.parse(JSON.stringify(users)),
    },
  };
}

---

How to use this collections in SSR & SSG

import connectToDb from "path";
import usersModel from "path";
export async function getStaticProps() {
  connectToDb();
  const users = await usersModel.find();
  return {
    props: {
      users: JSON.parse(JSON.stringify(users)),
    },
  };
}

---

timestamp & date

• for adding createdAt and updatedAt key and values

const schema = mongoose.Schema({
  username: {
    type: String,
    required: true,
  },
  email: {
    required: true,
    type: String,
  },
  password: {
    required: true,
    type: String,
    minLength: 8,
  },
}, timestamps : true);
// Capital&unplural
const usersModel = mongoose.models.User || mongoose.model("User", schema);
//if exist dont make it twice
export default usersModel;

---

make relation in MongoDB

• One to One
• One to Many
• Many to Many

we use another key and value key is for example : teacher : ObjectID("")

with this we make realtion but how to write the schema?

teacher : {
 type : mongoose.Types.ObjectId,
 ref:"Teacher"
 required :true
}

• here ref means this ObjectId is for which models?
• so in the ouptput we have problem we received datas from api like this {teacher : "jdfbi475bdewb34i0"}
• we dont want this so we want instaed of real id => shows us the {} that related to this key

for fix that : Populate()

const courses = await coursesModel.find({}).populate("KEY in object");

for example here

xyz : {
 type : mongoose.Types.ObjectId,
 ref:"Teacher"
 required :true
}

=====>
const courses = await coursesModel.find({}).populate("xyz");
//the key value in scheme object

in schema file also we should require teacherModel that we user theire data for relation in schema file

const teacherModel = require("./teacherModel");

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select or remove specific fileds that comes from relations data

• sometime we dont need all keys & values wo how to delete one item or only get one key or 2 key ...

if we want to say we need all data expect one of them we say "-price"

const users = await usersModle.find({}, "-__v0");

if we want to say we need one of them we say "price email"

const users = await usersModle.find({}, "_id email");
or;
const courses = await coursesModel
  .find({}, "-price")
  .populate("xyz", "_id -updatedAt");

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kind of Relations in MongoDB

• Refrence
• Embedded

- in past examle we user ref : "" to ref that collection model we have another way to make relation we called embedded

Embedded Relation

for make Embedded realtion when we use our schema we export that

export const teacherSchema = mongoose.Schema({});

======>
const teacherModel = require("./teacherModel");
const courseSchema = mongoose.Schema({
  teacher: {
    type: teacherModel,
    required: true,
  },
})

but here we need all teacher schema structure so first we get teached Schema

const mainSchema = await teachersModel.findOne({ _id: req.body.id });
const courses = await courseModel.create({ email, teacher: mainSchema });

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virtual relation

• when we create our schema after that we can say virtual relation is all about optimization in Database so in genrall our relation is not created but when you sent req in our response we can see the final result

const { commentsModel } = require("./comments");
schema.virtual("comments", {
  ref: "Comment",
  localField: "_id",
  foreignField: "course", // اون اسکیمایی که توش هستی
});

localfield is main model you are in there you say look at _id in this file and connect to another model is foreignField we say "course"

when you want to recieve that you say

const course = await courseModel
  .findOne({})
  .populate("name u enter in virtual || comments")
  .lean(); // return as array of obj

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validator package

• we can use validator package to validate our data fastest-validator

const Validator = require("fastest-validator");
const v = new Validator();
const schema = {
  title: { type: "string", min: 8, max: 100 },
  price: { type: "number", minLength: 0, psitive: true },
};
const check = v.complie(schema);
export default check
====>
import courseValidator from "@/validators/course"
const validationResult = courseValidator(req.body)
if(validationResult !== true){
  return res.status(422).json(validationResult)
}
//if everything is alright return => true
//if not , we have problem while validating return {}

• so with this package our DB never crash

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work With MongoSH

• for make change and insert or get and ...inside the mongoCompass GUI

for see how many database we already have :show dbs for select data base we say : use <your-DataBase-Name>

• so we in our database we have some collections we say : db.<collection-name>.find({}) or db.teachers.insertOne({SCHEMA})

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Middlewares in next js

• security checking for exmaple everybody can not access to some private routes in this structure we import NextResponse from "next/server" we made middleware.js file in root of project

import { NextResponse } from "next/server";
export function middleware(request) {
  if (request.nextUrl.pathname.startsWith("/users")) {
    //Validation if everything was ok so the NextResponse.next() will be execute
    return NextResponse.redirect(new URL("/login", request.url)); // dont return default so retun and redirect
  }
  return NextResponse.next(); //in default this code execute
}

we can also recieve users Cookis

request.cookies.get("")

matcher in MiddleWare

• we apple to this middlewares function execute in specific pages we want not into all pages

import { NextResponse } from "next/server";
import type { NextRequest } from "next/server";

// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  return NextResponse.redirect(new URL("/home", request.url));
}

// See "Matching Paths" below to learn more
export const config = {
  matcher: "/about", // this middleware only execute when you are in /about routes
};

//for all routes in specific path
//matcher : "/panel/:path*"
//or array
// matcher : ["/user", "/panel"]

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.env files

.env files is more safe place to write forexmaple our ports or our apiKeys there

• 1.make .env files in root of project

API_KEY = sdkndfkdfn;

• for access we say proccess.env.API_KEY

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2.Authenticating in Backend

packages we review in this document :

• Hash-Password
• JWT
• Cookies-manager

here we gonna to talk about all user auth and sign-in and sign-up ---