autoreply-editor/autoreply_editor/main.py

from autoreply_editor import app
from flask import Flask, request, render_template, redirect

@app.route("/")
def index():
    with open(app.config.get("MESSAGE_FILE"), "r") as f:
        message = f.read()

    return render_template("index.html", message=message)

@app.route('/', methods=['POST'])
def index_post():
    input_message = request.form['message'] + '\n'
    if request.method == 'POST':
        with open(app.config.get("MESSAGE_FILE"), 'w') as f:
            f.write(str(input_message))
    return redirect("/")