Python Flask Rest API

Python Flask is a microframework for the development of web apps. In this post you can discover out how to use Flask-RESTful to build RESTful APIs.

Flask-RESTful is a Python extension which adds assistance to build REST APIs quickly. It’s a simple abstraction that fits for the ORM / libraries.

Related course: Python Flask: Create Web Apps with Flask

Install

Before the application is created, we build a work environment that holds python packages installed apart from other applications.

You install virtualenv in order to build a virtual environment

sudo pip install virtualenv

Then you build and enable a virtual environment called venv

virtualenv venv
source venv/bin/activate

Then Flask & Flast-RESTful are installed into the virtual environment

pip install Flask
pip install flask-restful

Flask Rest API

Now, we have the resting flask library installed. A file called main.py must be created. Initially, you import flask as well as the module flask restful.

from flask import Flask
from flask_restful import Resource, Api

app = Flask(__name__)
api = Api(app)

We’ll build a small class. It’s code as follows:

class Quotes(Resource):
    def get(self):
        return {
            'bukowski': {
                'quote': ['Some people never go crazy. What truly horrible lives they must lead', 
                    'Can you remember who you were, before the world told you who you should be?'
                    ]
            },
            'angelou': {
                'quote': ['You will face many defeats in life, but never let yourself be defeated']
            }

        }

I’ve included static data in this case. You could have your own servers, as I said. Then we must add this class to the API library wrapper as a tool.

api.add_resource(Quotes, '/')

The code looks like this:

# -*- coding: utf-8 -*-

from flask import Flask
from flask_restful import Resource, Api

app = Flask(__name__)
api = Api(app)

class Quotes(Resource):
    def get(self):
        return {
            'bukowski': {
                'quote': ['Some people never go crazy. What truly horrible lives they must lead', 
                    'Can you remember who you were, before the world told you who you should be?'
                    ]
            },
            'angelou': {
                'quote': ['You will face many defeats in life, but never let yourself be defeated']
            }

        }

api.add_resource(Quotes, '/')

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

Start the script and it’ll output this:

~ » python api.py 
 * Serving Flask app "case" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 730-804-219

Open localhost:5000/ and it outputs the complete json object.

Related course: Python Flask: Create Web Apps with Flask

Resourceful routing

Create the script below:

from flask import Flask, request
from flask_restful import Resource, Api 

app = Flask(__name__)  
api = Api(app)
                                                                                                                                                           
users = {}

class UserSimple(Resource):
    def get(self, user_id):  
        return {user_id: users[user_id]}
                                                                                                                                                                   
    def put(self, user_id):
        users[user_id] = request.form['data']
        return {user_id: users[user_id]} 
                                                                                                                                                                   
api.add_resource(UserSimple, '/user/<string:user_id>')
                                                                                                                                                           
if __name__ == '__main__':
    app.run(debug=True)

Then in the server we add some users to users = {} by doing HTTP PUT requests. You can do so in the Python shell, simulating web browser requests.

>>> from requests import put,get
>>> 
>>> # PUT requests, add data
>>>
>>> put('http://localhost:5000/user/alice', data={'data': 'Alice'}).json()
{'alice': 'Alice'}
>>> put('http://localhost:5000/user/bob', data={'data': 'Bob'}).json()
{'bob': 'Bob'}
>>> 
>>> # GET requests, grab data
>>> 
>>> get('http://localhost:5000/user/alice').json()
{'alice': 'Alice'}
>>> get('http://localhost:5000/user/bob').json()
{'bob': 'Bob'}
>>>

You can do the GET requests in your web browser too:

Related course: Python Flask: Create Web Apps with Flask