Python Flask Primer In the Pycharm Professional Environment.

Flask is a popular simple and easy to learn framework for building interactive websites to handle forms, logins and pretty much anything you might use on the internet.

• Used heavily by companies such as Samsung, Netflix, Trivago, and Reddit -  1000's of jobs list Flask as part of the requiem required. It is used and popular!
• We are reviewing this excellent tutorial and full credit to DigitalOcean:

Let's get started.

Pycharm (professional) has native support for Flask. Starting a new project is this easy:

A small template will be built for you, and it is automatically setup to serve on Port 5000:

from flask import Flask

app = Flask(__name__)


@app.route('/')
def hello_world():  # put application's code here
    return 'Hello World!'


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

A basic explanation:

@app.route('/') 

Is a simple decorator that if one accesses the main page in this case:

http://127.0.0.1:5000/

It will serve the content 'Hello World!'

• It should be noted that Pycharm Professional really 'takes over' the handling of the port. Even with:

testing = False

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8080, debug=True)

It was still found to serve from port 5000, ignoring the app.run section of the code. We are required to run it in a separate terminal, even the Pycharm guide did not work:

flask run -h localhost -p 8080 

Generating html requests.

Pycharm Professional is powerful! You can easily generate a html request by clicking on the world icon as in:

Another entry will be created with a GET html set:

Each time you run it - it will have a time stamped reference of what each page looked like. It lets you modify the code and see the differential outputs:

Returning a file from the template directory.

• Flask will default serve from the template directory as in:

Which is served by simply,

from flask import Flask, render_template

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html', posts=posts)

The html code utilizes Jinga Templates. Consider the example:

{% extends 'base.html' %}

{% block content %}
    <h1>{% block title %} Welcome to FlaskBlog {% endblock %}</h1>
    {% for post in posts %}
        <a href="#">
            <h2>{{ post['title'] }}</h2>
        </a>
        <span class="badge badge-primary">{{ post['created'] }}</span>
        <hr>
    {% endfor %}
{% endblock %}

{% extends 'base.html' %}

• Flask by default will look and serve from the template folder, in this  case extending 'base.html'

{% block content %}

{% endblock}

• content is the name of the block.
• It then is referenced to whatever is being extended.
• Inside the 'base.html' we will find the following reference.

    <div class="container">
        {% block content %} {% endblock %}
    </div>

Passing Variables to the python render template.

The following code block shows how we poll a sqlite query and pass it for rendering inside the index.html:

@app.route('/')
def index():
    conn = get_db_connection()
    posts = conn.execute('SELECT * FROM posts').fetchall()
    conn.close()
    return render_template('index.html', posts=posts)

When it renders it will look like: