First off, this is all largely borrowed from RealPython and various other sites, pages, and people - not really anything that I have contributed organicly.
This is a simple 'quick n simple' Python-Flask application tutorial written for general useage of Python/Flask, forms processing (GUI), and local deployment/dubugging. This will help a new (but probably not noob) Pythonista learn how to set up a basic web server application in Python with Flask running on a local server, and assumes that the the developer is using Visual Studio Code as their IDE of choice.
Flask is a Model-View-Controller (MVC) framework (see this page for some insight to what MVC is and isnt, and also Real Python's MVC Explained page for more details.
This readme will walk through the steps to make a basic user-interactive web-application using Flask and Python (and a few other simple additions that are easy to install). If you just want to look at the final product, look at the app.py file where it is all completed and comments, docstrings, and more are added to help explain things.
Create the Python virtual environment - this only needs doing ONCE
python3 -m venv venv
Activate (e.g. use) the virtual enviroment - do this EVERY time
source venv/bin/activate
Create a 'requirements.txt' file that lists all of the libraries that we will use. For now, just add the following line:
Flask==1.1.2
Install the requirements file like so (update this file everytime you permanently add a library that you need to use and then rerun this command):
pip install -r requirements.txt
Create a file named app.py that is parallel to the requirements.txt file and the virtual environment (venv) folder with the following content:
from flask import Flask
app = Flask(__name__)
@app.route("/")
def index():
return "Hello World!"
Run this minimalist web application with the following commands:
export FLASK_ENV=development
export FLASK_APP=app.py
flask run
Exporting the FLASK_ENV as development enables some nice features that we will explore later on (see Visual Studio's Run the App Debugger page fore more info on how to setup/use it from within VS), and disables some anoying reminders to NOT use this in 'production' without a proper WSGI (or similar interface).
Exporting the FLASK_APP is not strictly necessary, since we are using the default name for our application python file, but it is a good idea to be fimiliar with the variable and it's usage.
Now that the applicatrion is running, browse the local system on port 5000 (typically http://localhost:5000/). When you do, you should see the friendly message "Hello World!" in your browser and the following in the terminal where the application is running:
❯ flask run
* Serving Flask app "app.py" (lazy loading)
* Environment: development
* Debug mode: on
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 290-425-530
127.0.0.1 - - [25/Apr/2021 12:04:00] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [25/Apr/2021 12:04:01] "GET /favicon.ico HTTP/1.1" 404 -
...TBD/In progress ;)