Python Flask — RESTful API

Lightweight microframework

Why :

1. Built-in development server and debugger
2. Integrated Unit Testing support
3. Easy and flexible configurations

Installation

Run command

 Python3 -m pip install Flask

Implementation

from flask import Flask
app = Flask(__name__)
@app.route(‘/’)
  def hello_world():
  return ‘Hello world’

Run / Start Server

flask run

API Endpoints

Let’s write our API endpoints in the app.py file.

Importing Libraries

from flask import Flask, jsonify, request
import logging

POST : Handling Request Body

@app.route(‘/api/v1/doa, methods=[‘POST’])
  def get_request_body():
  request_data = request.get_json()
  title = request_data[‘title’]
  return title

Send request with curl command :

curl — location — request POST ‘http://127.0.0.1:5000/api/v1/doa' \
 — header ‘Content-Type: application/json’ \
 — data-raw ‘{
“title”: “wuduk”
}’

GET : Handling Query Parameters

@app.route(‘/api/v1/doa/search’)
  def query_example():
  keyword = request.args.get(‘keyword’)
  logging.debug(‘keyword: %s’ % keyword)
  return keyword

Endpoint : http://127.0.0.1:5000/api/v1/doa/search?aktiviti=selamat

Handling Request Headers

@app.route(‘/api/v1/authorisation’, methods=[‘GET’])
def api_auth():
  if ‘Authorisation’ in request.headers:
  authkey = request.headers[‘Authorisation’]
  return authkey

Send request with curl command :

curl — location — request GET ‘http://127.0.0.1:5000/api/v1/authorisation' \
 — header ‘Authorisation: 32vffwfwr23423’ \
 — header ‘Content-Type: application/json’

GET : Handling URL Variables

@app.route(‘/api/v1/doa/<id>’, methods=[‘GET’])
def api_url_variable(id):
return id

Endpoint : http://127.0.0.1:5000/api/v1/doa/23

Default app.py

Run the following command if we want to change the main file, otherwise we can use the default app.py

export FLASK_APP=application.py

Database Connection : MySQL

pip3 install Flask flask-mysql

Write the following code in your main file .py :

from flaskext.mysql import MySQL
mysql = MySQL()
# MySQL configurations
app.config[‘MYSQL_DATABASE_USER’] = ‘your_user’
app.config[‘MYSQL_DATABASE_PASSWORD’] = ‘your_password’
app.config[‘MYSQL_DATABASE_DB’] = ‘your_database_name’
app.config[‘MYSQL_DATABASE_HOST’] = ‘your_host’
mysql.init_app(app)
@app.route(‘/api/v1/database’)
def api_database():
  cur = mysql.connect().cursor()
  cur.execute(‘’’select * from muslimbrader.doa’’’)
  r = [dict((cur.description[i][0], value)
  for i, value in enumerate(row)) for row in cur.fetchall()]
  return jsonify({‘data’ : r})

Endpoint : http://127.0.0.1:5000/api/v1/database

Response :

Werkzeug

Flask depends on the Jinja template engine and the Werkzeug WSGI toolkit. Werkzeug is primarily a utility library for WSGI (rather than web server) although it provides a simple web server for development purposes. WSGI itself is a protocol or convention that ensures that our web application can speak with the webserver and more importantly that web applications work nicely together.

Werkzeug summary as follow :

1. A comprehensive WSGI web application library
2. Does not have any direct dependencies

Example of response header (I used curl command with -i argument for this) :

HTTP/1.0 200 OK
Content-Type: text/html; charset=utf-8
Content-Length: 5
Server: Werkzeug/2.0.1 Python/3.8.5
Date: Sat, 24 Jul 2021 00:32:45 GMT