🎓 Node Js + Express Js + MongoDb

⚙️ Dependency Install

Link	description
Node Js	Install Node Js for backend.
MongoDb	Install MongoDb software for database.
Postman	Install Postman software for debugging

Postman also available in Vs Code as Extension. Search Postman

Now open powershell as administer.

Install nodemon in your system

Way install nodemon ?

:- Auto reloading server after changing code.

npm i nodemon -g

Set-ExecutionPolicy Unrestricted

📌 Node end Express Install

mkdir myBackend
cd myBackend

Now install Express in the myBackend directory and save it in the dependencies list. For example:

npm init

npm i express

📌 Run as a localhost.

create new file index.js.

const express = require('express')
const app = express()

const port = 8080
app.listen(port, () => {
  console.log(`Server Started : http://localhost:${port}`);
})

let's run in browser. nodemon for starting server.

PS D:\NodeExpress\backend> nodemon

🎉 Congratulation: Your local host started.

index.js

📌 Create server

const express = require("express");
const app = express();

const port = 7070;
app.listen(port, () => {
  console.log(`Server running... , http://localhost:${port}`);
});

📌 Create home page API

index.js

const express = require('express')
const app = express()

/* ----- */
app.get('/', (req, res) => {
  res.send("Hello Express")
})
/* ----- */

const port = 8080
app.listen(port, () => {
  console.log(`Server Started : http://localhost:${port}`);
})

🔺 multiple API

index.js

const express = require('express')
const app = express()

app.get('/', (req, res) => {
  res.send("Hello Express")
})

app.get('/about', (req, res) => {
  res.send("This is a about page")
})

const port = 8080
app.listen(port, () => {
  console.log(`Server Started : http://localhost:${port}`);
})

change localhost path end check output :- http://localhost:7070/about

📌 What is req (request) & res (response) ?

In Express.js, "request" and "response" are two fundamental objects used when handling HTTP requests and generating HTTP responses in your web applications. They represent the incoming request made by a client (usually a web browser) and the outgoing response that your server sends back to the client. Here's what each object represents:

**1. ** Request (req):

The req object represents the HTTP request made by the client. It contains information about the incoming request, such as the URL, HTTP method (GET, POST, etc.), request headers, request parameters, and any data sent in the request body.
You can access various properties and methods on the req object to retrieve data from the request, such as req.params, req.query, req.body, and req.headers.
You can also use req to perform tasks like authentication, validation, and processing the incoming data.

**2. ** Response (res):

The res object represents the HTTP response that your Express application will send back to the client. It's used to set response headers, send data to the client, and manage the response status.
You can use methods and properties on the res object to send data back to the client, including res.send(), res.json(), and res.render().
You can also set HTTP response headers using methods like res.set() and set the HTTP status code using res.status().

Here's a simple example of how you might use req and res in an Express route handler:

app.get('/example', (req, res) => {
  // Access request data
  const queryParam = req.query.paramName;
  
  // Send a response to the client
  res.status(200).send('Hello, World!');
});

In this example, the req object is used to access the query parameter paramName from the URL, and the res object is used to send the "Hello, World!" response with an HTTP status code of 200.

These objects are essential for building web applications in Express.js as they allow you to handle incoming requests and send appropriate responses to the client based on those requests.

🔺 get method

Respond with Hello World! on the homepage:

app.get('/', (req, res) => {
  res.send('Hello World!')
})

🔺 post method

Respond to POST request on the root route (/), the application’s home page:

app.post('/', (req, res) => {
  res.send('Got a POST request')
})

🔺 put method

Respond to a PUT request to the /user route:

app.put('/user', (req, res) => {
  res.send('Got a PUT request at /user')
})

🔺 delete method

Respond to a DELETE request to the /user route:

app.delete('/user', (req, res) => {
  res.send('Got a DELETE request at /user')
})

📌 Connect With mongoDb

create account in mongoDb database
create deployment

enter cluster username end password.

Click connect
Click Drives end copy the link

install mongoose

npm i mongoose

Create new dir configs end file databaseConnection.js.

/configs/databaseConnection.js

const { default: mongoose } = require("mongoose");

mongoose.connect("mongodb+srv://readme:readme@nodeexpress-readme.5sz7pau.mongodb.net/?retryWrites=true&w=majority").then(() => {
  console.log("Database Connected...");
})

require in index.js

index.js

// Some Code
require('./configs/databaseConnection')
// Some Code

📌 postData in mongodb.

🔺 Create models

Create new dir models end new file createData.js

create model in database.

/models/createData.js

const mongoose = require("mongoose");

const createData = mongoose.Schema({
  title: String,
});

const dataCreated = mongoose.model("createdData", createData);

module.exports = dataCreated;

🔺 create controllers (API)

Create new dir controllers end new file postData.js

data detail end save data in mongodb.

/controllers/postData.js

const createData = require("../models/createData.js");

const postData = async (req, res) => {
  console.log(req.body);
  const data = createData({
    title: req.body.title,
  });

  await data.save();
};

module.exports = postData;

Now require end use.

index.js

const express = require('express')
const app = express()

// is require
// database side data store in json formate.
app.use(express.json())

// require API
const postData = require("./controllers/postData.js");

app.get('/', (req, res) => {
  res.send("Server is live 🟢")
})

// use API with post method
app.post("/data", postData);

const PORT = 8080
app.listen(PORT, () => {
  console.log(`Server Connected : http://localhost:${PORT}`);
})

🔺 postData with postman

Create a new collection.
select post method
Enter localhost url end path.
Select body > row > json
add json form data
end send
sending process is continue running than your data is sending successfully

check mongodb database cluster data is added.

🔺 getData method

/controllers/getData.js

const createData = require("../models/createData");

const getData = async (req, res) => {
  let data = await createData.find({});
  console.log(data);
  res.send({ process: true, data });
};

module.exports = getData;

index.js

const getData = require("./controllers/getData.js");
// Some Code
app.get("/getData", getData);

🔺 getData with postman

click get
enter url with path

🔺 deleteData method

/controllers/deleteData.js

const createData = require("../models/createData");

const deleteData = async (req, res) => {
  const id = req.params.id
  await createData.findByIdAndDelete(id)
}

module.exports = deleteData

📌 createData, postData, getAllData end getCategoryData method

🔺 createData method

create a new products models

models/createProductData.js

const mongoose = require("mongoose")

const createProductData = mongoose.Schema({
  category: String,
  brand: String,
  img_1: String,
  img_2: String,
  img_3: String,
  title: String,
  weight: String,
  price: Number,
  discount: Number
})

const productData = mongoose.model("productData", createProductData)

module.exports = productData

🔺 postData method

create new controllers

/controllers/postProductData.js

const createdProductData = require("../models/createProductData")

const postProductData = async (req, res) => {
  console.log(req.body);
  const data = createdProductData({
    category: req.body.category,
    brand: req.body.brand,
    img_1: req.body.img_1,
    img_2: req.body.img_2,
    img_3: req.body.img_3,
    title: req.body.title,
    weight: req.body.weight,
    price: req.body.price,
    discount: req.body.discount,
  })

  await data.save()
}

module.exports = postProductData

index.js

const postProductData = require("./controllers/postProductData.js");
// Some Code
app.post("/postProductData", postProductData)

🔺 getAllData method

create new controllers

/controllers/getProductData.js

const createdProductData = require("../models/createProductData")

const getProduct = async (req, res) => {
  let data = await createdProductData.find({})
  console.log(data);
  res.send({ process: true, data })
}

module.exports = getProduct

index.js

const getProduct = require("./controllers/getProductData.js");
//Some Code
app.get("/getAllProducts", getProduct)

🔺 getCategoryData method

create new controllers

/controllers/getProductsByCategory.js

const productData = require("../models/createProductData");

let getProductsByCategory = async (req, res) => {
  let productCategory = await productData.find({ category: req.params.products })
  console.log(productCategory);
  res.send({ process: true, productCategory })
}

module.exports = getProductsByCategory

index.js

const getProductsByCategory = require("./controllers/getProductsByCategory.js");
// Some Code
app.get("/products/category/:products", getProductsByCategory)