====== Flask ======

> Flask is a micro web framework written in Python. It is classified as a microframework because it does not require particular tools or libraries. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions. However, Flask supports extensions that can add application features as if they were implemented in Flask itself. Extensions exist for object-relational mappers, form validation, upload handling, various open authentication technologies and several common framework related tools.
>
> https://en.wikipedia.org/wiki/Flask_(web_framework)

===== Installation =====

Create an environment:

<code bash>
mkdir myproject

cd myproject

python3 -m venv .venv
</code>

Activate the environment:

<code bash>
. .venv/bin/activate
</code>

Install Flask:

<code bash>
pip3 install Flask
</code>

Source: https://flask.palletsprojects.com/en/2.3.x/installation/

===== Quick Start =====

Minimal application:

<file python hello.py>
from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"
</file>

Run dev server:

<code bash>
flask --app hello run
</code>

<code>
 * Serving Flask app 'hello'
 * Running on http://127.0.0.1:5000 (Press CTRL+C to quit)
</code>

Access from browser: http://127.0.0.1:5000/

Result:

<code>
Hello, World!
</code>

Source: https://flask.palletsprojects.com/en/2.3.x/quickstart/

{{tag>python}}