Simple REST API using Flask

In this tutorial we will learn a simple REST API using Flask. We will learn mostly two methods (GET and POST) of HTTP request.

Content

• Dependencies
• Creating a flask app
• GET Method
• POST Method

Dependencies

To start with this tutorial, let’s import the required packages.

pip install flask

Creating a flask app

Creating a flask app is quite simple.

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello World!'

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

run following command to test

python app.py

GET Method

The GET method is used to retrieve data from a server. Here we will retrive simple message from our local server. Modify the above code with a new route and a new function with GET method.

from flask import Flask, jsonify, request

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello World!'

@app.route('/get_message', methods=['GET'])
def get_message():
    return jsonify({'message': 'Hello World!'})

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

To get the message we will use python requests module to retrive the message.

import requests

response = requests.get('http://localhost:5000/get_message')
print(response.json())
# output: {'message': 'Hello World!'}

POST Method

The POST method is used to send data to a server. Here we will send text to our local server, our server will tokenize it and return tokenized data. Modify the above code with a new route and a new function with POST method.

from flask import Flask, jsonify, request

app = Flask(__name__)

@app.route('/')
def hello():
    return 'Hello World!'

@app.route('/get_message', methods=['GET'])
def get_message():
    return jsonify({'message': 'Hello World!'})

@app.route('/tokenize', methods=['POST'])
def tokenizer():
    if request.method == 'POST':
        data = request.json
        text = data['text']
        tokens = text.split()
        return jsonify({'tokens': tokens})

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

To send the text we will use python requests module to send the text.

import requests

data = {'text': 'Hello World!'}
response = requests.post('http://localhost:5000/tokenize', json=data)
print(response.json())
# output: {'tokens': ['Hello', 'World!']}