How to create a simple Flask API for hello world?

Published on : July 25,2022

REST stands for Representational State Transfer and is an architectural style used in modern web development. It defines a set of rules/constraints for a web application to send and receive data. In this article, we are going to learn how to create a simple REST API that returns ‘Hello World’, with the help of a flask.

In this article we are going to write a simple flask API for hello world using two methods:

Using Flask jsonify object.
Using the flask_restful library with Flask.

Installation

1. Install the python Flask library using the following command.

pip install Flask

2. Install the flask-restful library using the following command.

pip install Flask-RESTful

Method 1: Using Flask ‘jsonify’ object

Create a new python file named ‘main.py’.
import Flask, jsonify and request from the flask framework.
Register the web app into an app variable using the following syntax.
Python3

app =   Flask(__name__)

Create a new function named ‘helloworld’. This function is going to return the ‘Hello World’ text in JSON format.
Route the ‘helloworld’ function to your desired URL using the following syntax.

@app.route('/path_of_the_response', methods=['GET'])
def helloworld():
    pass

Inside the ‘helloworld’ function if request method is ‘GET’ then create a python dictionary with the ‘Hello World’ message.
Jsonify the python dictionary and return it.
Build the flask application using the following command.

if __name__ == '__main__':
    app.run(debug=True)

Run the ‘main.py’ file in the terminal or the IDE and type the following URL in the browser.

http://127.0.0.1:5000/hello

Code : Python3

from flask import Flask, jsonify, request

app = Flask(__name__)


@app.route('/hello', methods=['GET'])
def helloworld():
	if(request.method == 'GET'):
		data = {"data": "Hello World"}
		return jsonify(data)


if __name__ == '__main__':
	app.run(debug=True)

Output :

Method 2: Using the flask_restful library

Create a new python file named ‘main.py’.
Import Flask from the flask framework.
Import API and Resource from the ‘flask_restful’ library.
Register the web app into a app variable using the following syntax.

app =   Flask(__name__)

api = Api(app)

Create a resource class named ‘HelloWorld’.
Inside the resource class, create a ‘get’ method.
Return a dictionary with the ‘Hello World’ message from the ‘get’ method.
Add the resource class to the API using the add_resource method.
Build the flask application using the following command.

if __name__ == '__main__':
	app.run(debug=True)

Run the ‘main.py’ file in the terminal or the IDE and type the following URL in the browser.

http://127.0.0.1:5000/hello

from flask import Flask
from flask_restful import Api, Resource

app = Flask(__name__)

api = Api(app)

class HelloWorld(Resource):
	def get(self):
		data={"data":"Hello World"}
		return data

api.add_resource(HelloWorld,'/hello')


if __name__=='__main__':
	app.run(debug=True)

Output

Categories : Python

Tags : Python Flask API

Praful Sangani

I'm a passionate full-stack developer with expertise in PHP, Laravel, Angular, React Js, Vue, Node, Javascript, JQuery, Codeigniter, and Bootstrap. I enjoy sharing my knowledge by writing tutorials and providing tips to others in the industry. I prioritize consistency and hard work, and I always aim to improve my skills to keep up with the latest advancements. As the owner of Open Code Solution, I'm committed to providing high-quality services to help clients achieve their business goals.