I followed the instructions for serving favicons from Flask's docs, and added the line app.add_url_rule('/favicon.ico', redirect_to=url_for('static', filename='favicon.ico')) to my server. But when I run it I get this error:
File "server.py", line X, in __init__
redirect_to=url_for('static', filename='favicon.ico'))
File "/python3.9/site-packages/flask/helpers.py", line 306, in url_for
raise RuntimeError(
RuntimeError: Attempted to generate a URL without the application context being pushed. This has to be executed when application context is available.
I am using a class-based server, with the basics reproduced here:
from flask import Flask, Response, render_template, request, redirect, url_for
from werkzeug.exceptions import HTTPException
class Server:
def __init__(self, host, port):
self.app = Flask(__name__)
self.host = host
self.port = port
# Set up routes:
self.app.route("/")(self.index)
# Error occurs here:
self.app.add_url_rule('/favicon.ico',
redirect_to=url_for('static', filename='favicon.ico'))
self.app.register_error_handler(HTTPException, self.handle_http_error)
def index(self):
return render_template("index.html")
@staticmethod
def error(msg):
"""Custom error handler"""
return render_template("error.html", msg=msg)
def handle_http_error(self, e):
return self.error(f"{e.code} {e.name}: {e.description}"), e.code
def start(self):
self.app.run(host=self.host, port=self.port)
server = Server("localhost", 8080)
server.start()
My guess is I put the line to serve the favicon in the wrong spot. The error message says This has to be executed when application context is available., but I'm not sure exactly what that means. I saw this question but the answer is a bit vague, and I couldn't figure out how to incorporate it into my code. Also, that user had a with statement, which I tried but couldn't get to work. I tried adding a SERVER_NAME config variable but it didn't change anything (I also had no idea what to put in it, so that's probably another issue).
