Repository Design Pattern

 const mysql = require('mysql');

// Repository interface

class UserRepository {

constructor(connection) {

this.connection = connection;

}

getById(id) {

return new Promise((resolve, reject) => {

this.connection.query('SELECT * FROM user WHERE id = ?', [id], (error, results) => {

if (error) {

reject(error);

} else {

resolve(results[0]);

}

});

});

}

save(user) {

return new Promise((resolve, reject) => {

this.connection.query('INSERT INTO user SET ?', user, (error, result) => {

if (error) {

reject(error);

} else {

resolve(result.insertId);

}

});

});

}

}

// Create a connection to the MySQL database

const connection = mysql.createConnection({

host: 'localhost',

user: 'root',

password: 'sangram#81',

database: 'playground'

});

connection.connect();

// Client

const userRepository = new UserRepository(connection);

const user = { id: 1, name: "Alice" };

userRepository.save(user)

.then(insertedId => {

console.log(`User inserted with ID: ${insertedId}`);

return userRepository.getById(insertedId);

})

.then(retrievedUser => {

console.log("Retrieved user:", retrievedUser);

})

.catch(error => {

console.error("Error:", error);

})

.finally(() => {

connection.end(); // Close the database connection

});