10.
Develop an express web application that can interact with REST
API to perform CRUD operations on student data. (Use Postman)
Solution :
Firstly we need to create a new folder and open the folder in the command
prompt and enter a command as below:
npm init -y
Open that folder in the vscode by entering code.
Next in the terminal we need to install all the packages we need, so we mainly
use express and sqlite3.
The Command to install express and sqlite3 is
npm install express sqlite3
Then create file named as the app.js and db.js
package.js
{
"name": "10",
"version": "1.0.0",
"main": "index.js",
"scripts": {
"start": "node app.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
"keywords": [],
"author": "",
"license": "ISC",
"description": "",
"dependencies": {
"express": "^5.1.0",
"sqlite3": "^5.1.7"
}
}
db.js
const sqlite3 = require('sqlite3').verbose();
// Function to initialize the database schema
function initializeDatabase() {
const db = new sqlite3.Database('./mydatabase.db', (err) => {
if (err) {
console.error(err.message);
} else {
console.log('Connected to the SQLite database.');
createStudentsTable(db);
}
});
// Close the database connection when the Node process exits
process.on('exit', () => {
db.close((err) => {
if (err) {
console.error(err.message);
} else {
console.log('Disconnected from the SQLite database.');
}
});
});
}
// Function to create the 'students' table if it doesn't exist
function createStudentsTable(db) {
const createTableQuery = `
CREATE TABLE IF NOT EXISTS students (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT,
age INTEGER,
grade TEXT
);
`;
db.run(createTableQuery, (err) => {
if (err) {
console.error(err.message);
} else {
console.log('The students table has been created or already
exists.');
}
});
}
module.exports = { initializeDatabase };
app.js
const express = require('express');
const sqlite3 = require('sqlite3');
const{ initializeDatabase } = require('./db');
const app = express();
const port = 3000;
// Initialize the database and create tables
initializeDatabase();
// Connect to SQLite database
const db = new sqlite3.Database('./mydatabase.db', (err) => {
if (err) {
console.log(err.message);
} else {
console.log('Connected to the SQLite database.');
}
});
// Middleware to parse request body as JSON
app.use(express.json());
app.get('/', (req, res) => {
res.send('Welcome to the Student');
});
// Get all Students
app.get('/students', (req, res) => {
db.all('SELECT * FROM students', [], (err, rows) => {
if (err) {
return console.error(err.message);
}
res.json(rows);
});
});
// Get a single student by id
app.get('/students/:id', (req, res) => {
const id = req.params.id;
db.all('SELECT * FROM students WHERE id = ?', [id], (err, row) => {
if (err) {
return console.error(err.message);
}
res.json(row);
});
});
// Create a new student
app.post('/students', (req, res) => {
const{ name, age, grade } = req.body;
db.run('INSERT INTO students (name, age, grade) VALUES (?, ?, ?)', [name,
age, grade], function (err) {
if (err) {
return console.error(err.message);
}
res.status(201).json({ id:this.lastID });
});
});
// Update a student
app.put('/students/:id', (req, res) => {
const id = req.params.id;
const{ name, age, grade } = req.body;
db.run('UPDATE students SET name = ?, age = ?, grade = ? WHERE id = ?',
[name, age, grade, id], function (err) {
if (err) {
return console.error(err.message);
}
res.json({ updatedID:id });
});
});
// Delete a student
app.delete('/students/:id', (req, res) => {
const id = req.params.id;
db.run('DELETE FROM students WHERE id = ?', id, function (err) {
if (err) {
return console.error(err.message);
}
res.json({ deletedID:id });
});
});
app.listen(port, () => {
console.log(`Server running at http://localhost:${port}`);
});
OUTPUT
