Flask is one of the most widely used python micro-frameworks to design a REST API. In this article, we are going to learn how to create a simple REST API that returns a simple JSON object, with the help of a flask.
Prerequisites: Introduction to REST API
What is a REST API?
REST stands for Representational State Transfer and is an architectural style used in modern web development. It defines a set or rules/constraints for a web application to send and receive data. In this article, we will build a REST API in Python using the Flask framework. Flask is a popular micro framework for building web applications.
Approaches: We are going to write a simple flask API that returns a JSON response using two approaches:
- Using Flask jsonify object.
- Using the flask_restful library with Flask.
Libraries Required:
- Install the python Flask library using the following command:
pip install Flask
- Install the flask-restful library using the following command:
pip install Flask-RESTful
Approach 1: Using Flask jsonify object – In this approach, we are going to return a JSON response using the flask jsonify method. We are not going to use the flask-restful library in this method.
- 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.
app = Flask(__name__)
- Create a new function named ‘ReturnJSON’. This function is going to return the sample JSON response.
- Route the ‘ReturnJSON’ function to your desired URL using the following syntax.
@app.route('/path_of_the_response', methods = ['GET'])
def ReturnJSON():
pass
- Inside the ‘ReturnJSON’ function if the request method is ‘GET’ then create a python dictionary with the two elements 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.
Code:
Python3
from flask import Flask,jsonify,request app = Flask(__name__) @app.route('/returnjson', methods = ['GET'])def ReturnJSON(): if(request.method == 'GET'): data = { "Modules" : 15, "Subject" : "Data Structures and Algorithms", } return jsonify(data) if __name__=='__main__': app.run(debug=True) |
Output:
Approach 2: Using the flask_restful library with Flask – In this approach, we are going to create a simple JSON response with the help of the flask-restful library. The steps are discussed below:
- 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 an app variable using the following syntax.
app = Flask(__name__)
- Register the app variable as an API object using the API method of the ‘flask_restful’ library.
api = Api(app)
- Create a resource class named ‘ReturnJSON’.
- Inside the resource, the class creates a ‘get’ method.
- Return a dictionary with the simple JSON response 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.
Code:
Python3
from flask import Flaskfrom flask_restful import Api, Resource app = Flask(__name__) api = Api(app) class returnjson(Resource): def get(self): data={ "Modules": 15, "Subject": "Data Structures and Algorithms" } return data api.add_resource(returnjson,'/returnjson') if __name__=='__main__': app.run(debug=True) |
Output:
