part_1_settingDB_postman.md

Backend Setup:

1. Import Necessary Modules: Start by importing the required libraries at the top of your server.js or your main application file.

   const express = require('express');
   const bodyParser = require('body-parser');
   const { Pool } = require('pg');

2. Initialize Express and PostgreSQL:

   Configure PostgreSQL by establishing a connection using pg.

   const app = express();
   
   const pool = new Pool({
      user: 'your_username',
      host: 'localhost',
      database: 'schoolDB',
      password: 'your_password',
      port: 5432,
   });
   
   // Middlewares
   app.use(bodyParser.json());

3. Define CRUD Routes:

   a. GET all students:

   app.get('/students', async (req, res) => {
      try {
          const result = await pool.query('SELECT * FROM students');
          res.json(result.rows);
      } catch (error) {
          res.status(500).json({ message: 'Internal server error' });
      }
   });

   b. POST a new student:

   app.post('/students', async (req, res) => {
      try {
          const { name, grade } = req.body;
          const result = await pool.query('INSERT INTO students (name, grade) VALUES ($1, $2) RETURNING *', [name, grade]);
          res.status(201).json(result.rows[0]);
      } catch (error) {
          res.status(500).json({ message: 'Internal server error' });
      }
   });

   c. PUT (update) an existing student:

   app.put('/students/:id', async (req, res) => {
      try {
          const { name, grade } = req.body;
          const result = await pool.query('UPDATE students SET name = $1, grade = $2 WHERE id = $3 RETURNING *', [name, grade, req.params.id]);
          if (result.rows.length) {
              res.json(result.rows[0]);
          } else {
              res.status(404).json({ message: 'Student not found' });
          }
      } catch (error) {
          res.status(500).json({ message: 'Internal server error' });
      }
   });

   d. DELETE a student:

   app.delete('/students/:id', async (req, res) => {
      try {
          const result = await pool.query('DELETE FROM students WHERE id = $1 RETURNING *', [req.params.id]);
          if (result.rows.length) {
              res.json({ message: 'Student deleted successfully' });
          } else {
              res.status(404).json({ message: 'Student not found' });
          }
      } catch (error) {
          res.status(500).json({ message: 'Internal server error' });
      }
   });

4. Start the server:

   const PORT = 3000;
   app.listen(PORT, () => {
       console.log(`Server is running on port ${PORT}`);
   });

   Use the command below to start the server:

   nodemon server.js

Testing with Postman:

1. Launch Postman.

2. GET all students: Set the HTTP method to GET and use the URL http://localhost:3000/students. Hit Send.

3. Add a student: Switch to POST, set the URL to http://localhost:3000/students, and use the 'Body' tab to input student details in JSON format. Click Send.

4. Update a student: Use PUT, adjust the URL to http://localhost:3000/students/[STUDENT_ID] replacing [STUDENT_ID] with a valid ID, and change the student's details in the 'Body' tab. Hit Send.

5. Delete a student: Change the HTTP method to DELETE, modify the URL to http://localhost:3000/students/[STUDENT_ID] where [STUDENT_ID] is the ID of the student you want to remove, and press Send.