01 How to Build a Simple Flask application

Today we create a simple demonstration of Flask and how we use its simple routing functions to display some quotes on a browser.

Setting up the environment

. Make sure you have set up a virtual environment . Add flask to this environment conda create --name FlaskSimple flask

Then activate the virtual environment: source activate FlaskSimple

. Make a directory called ‘app’ and under that another directory, quotes mkdir app and cd app , mkdir quotes

Setting up File Structure

. move to the app directory cd app . create two files and call them app.py and quotes.py touch app.py touch quotes.py

Setting up the data

. move to the quotes directory . create a file called quotes.py and start a simple dictionary:

def funny_quotes():
    return [{
        'author': 'author1',
        'quote': 'Hi'
            },

        {
        'author': 'author2',
        'quote': 'Ho'
        },

        {
        'author': 'author3',
        'quote':'Hee'
        },

        {
        'author': 'author4',
        'quote': 'Heh'
        }
    ]

Setting up the Flask app

cd .. will get you one level up from the quotes directory . open up the app.py file with your basic editor . create the following code:

from flask import Flask, jsonify
import random
from quotes import funny_quotes

app = Flask(__name__)


@app.route("/")
def serve_funny_quote():
    quotes = funny_quotes()
    nr_of_quotes = len(quotes)
    selected_quote = quotes[random.randint(0, nr_of_quotes - 1) ]
    return jsonify(selected_quote)

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

Viewing the Flask app results

. For the most part you are done making the simple Flask app. . Now it’s necessary to start up the app and view its results on the browser: python app.py will get you this result on your terminal:

127.0.0.1 - - [06/Sep/2017 15:33:28] "GET /?__debugger__=yes&cmd=resource&f=console.png HTTP/1.1" 200 -
 * Detected change in '/home/mbira/Dropbox/Projects/33FlaskSimple/app.py', reloading
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 174-255-069
127.0.0.1 - - [06/Sep/2017 15:34:13] "GET / HTTP/1.1" 200 -

Go to your browser and you will see the random choice of quotes from the quotes.py file:

// 20170906153440
// http://127.0.0.1:5000/

{
  "author": "author3",
  "quote": "Hee"
}

And that’s it. A simple Flask app routed to your browser.