• Code_student.zip

POST

In REST (Representational State Transfer), POST is one of the main HTTP methods — just like GET, PUT, PATCH, and DELETE.

Each method describes what kind of action the client wants the server to perform.

POST = Create a New Resource

When a client sends a POST request, it’s asking the server to add new information.

What Happens

• The client sends data to the server (using the POST method).

• The server receives it and creates a new record (e.g., a new student in the database).

• The server responds with a status code 201 (Created) and returns the newly created object — often with an assigned ID.

Request

POST /api/students

Body

{
  "name": "Thomas",
  "course": "Informatics"
}

Response:

{
  "id": 15,
  "name": "Thomas",
  "course": "Informatics"
}

POST Request Structure (http structure)

POST /api/students HTTP/1.1
Host: example.com
Content-Type: application/json

{
  "name": "Thomas",
  "course": "Informatics"
}

Step-by-Step

1. activate Body-Parser

const express = require("express");
const app = express();
// **NEW** activate Body-Parser
app.use(express.json());

This allowes Express to use req.body.

If a request has JSON data in its body, automatically read it and convert it into a JavaScript object that I can use.

Without express.json(), you’d have to manually handle raw data — it would just look like unreadable text.

With app.use(express.json()), Express automatically parses that data, and you can access it easily as:

req.body.name    // "Thomas"
req.body.course  // "Informatics"

2. POST-Route hinzufügen

Add below the GET-route (/students/:id) the new route:

// **NEW** add 1 Student
app.post("/students", (req, res) => {
  const { name, course } = req.body;

  // check if the JSON includes name and course 
  if (!name || !course) {
    return res.status(400).json({ error: "Name and course are required!" });
  }

  // Create a new ID (simple add 1 to the last ID in the array)
  const newId = students.length ? students[students.length - 1].id + 1 : 1;

  // Create a new Student
  const newStudent = { id: newId, name, course };
  
  // Add the new Student to the array
  students.push(newStudent);

  // Returns OK and the newStudent as a JSON Object
  res.status(201).json(newStudent);
});

const { name, course } = req.body;

That line uses a JavaScript feature called object destructuring to easily extract data from an object — in this case, from req.body.

It creates two variables: name and course.

Same:

const name = req.body.name;
const course = req.body.course;

if (!name || !course) { return res.status(400).json({ error: "Name and course are required!" }); }

Part	Meaning
if (!name \|| !course)	Checks if the user forgets to include either the name or the course in the request.
return	Stops running the rest of the function — nothing below this line will execute.
res.status(400)	Sets the HTTP status code to 400, which means Bad Request — the client sent invalid or incomplete data.
.json({ error: "Name and course are required!" })	Sends a JSON response back to the client with an error message.

const newId = students.length ? students[students.length - 1].id + 1 : 1;

Part	Meaning
students.length	Checks how many items (students) are in the array.
? ... : ...	This is the ternary operator, a short version of an if/else statement.
students[students.length - 1].id + 1	If the array is not empty, get the last student’s ID and add 1 to it.
1	If the array is empty, start with ID = 1.

Same:

let newId;
if (students.length > 0) {
  newId = students[students.length - 1].id + 1;
} else {
  newId = 1;
}

const newStudent = { id: newId, name, course };

Part	Meaning
const	Declares a constant variable — newStudent cannot be reassigned later.
newStudent	The name of the variable that will store the new student’s data.
{ ... }	Creates a JavaScript object with properties (key–value pairs).
id: newId	The property id is assigned the value of the variable newId.
name	Shorthand for name: name — it takes the value from the variable name.
course	Shorthand for course: course — it takes the value from the variable course.

Same:

const newStudent = {
  id: newId,
  name: name,
  course: course
};

students.push(newStudent);

Part	Meaning
students	This is an array that holds all the current student objects. Example: [{ id: 1, name: "Anna" }, { id: 2, name: "Ben" }]
.push()	A JavaScript array method that adds a new element to the end of the array.
newStudent	The object you want to add — for example, { id: 3, name: "Thomas", course: "Informatics" }.

It adds the new student object (newStudent) to the students array.

res.status(201).json(newStudent);

Part	Meaning
res	The response object — used by Express to send data back to the client (like Postman, a browser, or another app).
.status(201)	Sets the HTTP status code of the response to 201, which means “Created.”
.json(newStudent)	Sends the data newStudent as a JSON-formatted response body.

It sends a 201 Created response with the newly created student object in JSON format.

Test

Check:

$ npm run dev

> student@1.0.0 dev
> nodemon server.js

[nodemon] 3.1.10
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,cjs,json
[nodemon] starting `node server.js`
Server running at http://localhost:3000
[nodemon] restarting due to changes...
[nodemon] starting `node server.js`
Server running at http://localhost:3000

curl Request:

curl -X POST http://localhost:3000/students \
  -H "Content-Type: application/json" \
  -d '{"name":"Katrin","course":"BWL"}'

JSON Response:

{ "id": 11, "name": "Katrin", "course": "BWL" }

GIT

Do not forget to commit and push your work.

Azure

Deploy the app.

Test the app - just use the Azure URL

$ curl -X POST https://griesmayerstudent-apbdbxe7bwf9cjax.swedencentral-01.azurewebsites.net/students   -H "Content-Type: application/json"   -d '{"name":"Katrin","course":"BWL"}'
{"id":11,"name":"Katrin","course":"BWL"}