Day 27 of #100DaysOfCode — REST API

Source: Dev.to

What Is a REST API?

Think of a REST API like a waiter in a restaurant:

• You (the client/app) request food.
• The kitchen (server/database) prepares it.
• The waiter (REST API) takes your request, delivers it, and brings the result back.

You never go into the kitchen; you communicate only through the waiter — using standard, agreed‑upon phrases.

So What Is REST?

REST (Representational State Transfer) is a set of rules that allow two applications to communicate over the internet. The client uses standard HTTP methods to talk to a server and fetch or change data.

Core HTTP Methods in REST APIs

Real-World Example of a REST API

When your weather app loads, it might send a request like this:

GET https://api.weather.com/city=karachi

The server responds with JSON data:

{
  "city": "Karachi",
  "temperature": "31°C",
  "condition": "Sunny"
}

Your app displays the weather — thanks to the API.

What Is a “Resource” in REST?

A resource is any piece of data your API deals with.

Examples

• users
• posts
• products
• orders

Each resource has a unique URL (called an endpoint):

/users
/posts
/products

RESTful Route Naming Rules

REST focuses on nouns, not verbs.

Correct RESTful Routes

Get all users

GET /users

Create a user

POST /users

Get a single user

GET /users/:id

Update a user

PUT /users/:id
PATCH /users/:id

Delete a user

DELETE /users/:id

Wrong Route Naming (don’t do this)

POST /createUser
GET /getAllUsers
DELETE /deleteUser

These use verbs in the URL, which breaks REST conventions.

Query Parameters in REST APIs

Query parameters allow filtering, searching, or customizing results.

GET /users?role=admin
GET /products?limit=10&page=2
GET /posts?sort=latest

Request & Response Structure

Request

• params – values inside the URL (e.g., /users/:id)
• query – filtering/pagination (e.g., ?page=2)
• body – data for POST/PUT/PATCH requests
• headers – metadata (auth tokens, content‑type, etc.)

Response

• status code
• JSON body
• headers
• optional metadata (pagination info, timestamps, etc.)

Common REST API Status Codes

Success

• 200 OK – Request successful
• 201 Created – New resource created
• 204 No Content – Successful but no response body

Client Errors

• 400 Bad Request – Invalid input
• 401 Unauthorized – Authentication needed
• 403 Forbidden – Authenticated but not allowed
• 404 Not Found – Resource doesn’t exist

Server Errors

• 500 Internal Server Error – Something broke on the server

Idempotency in REST

“Idempotent” means sending the same request multiple times yields the same result.

Final Summary

A REST API is a messenger between your app and a server. It lets you create, read, update, and delete data using standard HTTP methods. If you understand:

• resources
• routes
• verbs (GET, POST, PUT, DELETE)
• query parameters
• status codes
• idempotency

…then you already grasp the core of REST APIs.

Happy coding!