How to debug a Flask app

Question

How are you meant to debug errors in Flask? Print to the console? Flash messages to the page? Or is there a more powerful option available to figure out what\'s happening

Answer 1

One can also use the Flask Debug Toolbar extension to get more detailed information embedded in rendered pages.

from flask import Flask
from flask_debugtoolbar import DebugToolbarExtension
import logging

app = Flask(__name__)
app.debug = True
app.secret_key = 'development key'

toolbar = DebugToolbarExtension(app)

@app.route('/')
def index():
    logging.warning("See this message in Flask Debug Toolbar!")
    return ""

Start the application as follows:

FLASK_APP=main.py FLASK_DEBUG=1 flask run