create-a-rest-api-using-flask-restful.md

Create A REST API Using Flask Restful

Category: Python

You can create a REST API in Python using flask-restful.

This TIL will show how to create a simple REST API with two methods:

• HTTP GET which processes a query param and sends a JSON response
• HTTP GET which processes a path param and sends a JSON response

Create a file called rest_api.py with the following content:

from flask import Flask, jsonify
from flask_restful import request, Resource, Api
import math
  
app = Flask(__name__)
api = Api(app)
  
# API GET endpoint which uses a query param
class SquareNumber(Resource):
  
    def get(self):
        try:
          num = int(request.args.get('number'))
          return jsonify({'result': num ** 2})
        except:
          # Return HTTP 400
          return ('Invalid request'), 400

# API GET endpoint which uses a path param
class SquareRoot(Resource):
  
    def get(self, num):
        return jsonify({'result': math.sqrt(num)})

api.add_resource(SquareNumber, '/square')
api.add_resource(SquareRoot, '/square-root/<int:num>')

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

Start the API:

python3 rest_api.py

Call the /square endpoint to calculate the square of a given number using a query param:

curl http://localhost:5000/square?number=54

Output:

{
  "result": 2916
}

Call the /square-root endpoint to calculate the square root of a given number using a path param:

http://localhost:5000/square-root/16

{
  "result": 4.0
}