Python3 Flask и Sqlite3 – невозможно вставить в базу данных

Я не могу заставить свой код работать. Я искал учебники и руководства, но безрезультатно. Если кто-нибудь увидит ошибку, которую я делаю, это было бы очень полезно.

Вот структура папок:

/
 application.py
 database.db

/routes
     __init__.py
     signup.py
    
/templates
     signup.html

Вот мой файл signup.py:

import sqlite3
from flask import Blueprint, render_template, redirect, session, request, flash
from werkzeug.exceptions import default_exceptions, HTTPException, InternalServerError
from werkzeug.security import check_password_hash, generate_password_hash

# Set Blueprints
signup = Blueprint('signup', __name__,)

@signup.route("/signup", methods=["GET", "POST"])
def signupFunction():

    # Forget any user_id
    session.clear()

    # User reached route via POST (as by submitting a form via POST)
    if request.method == "POST":

        try:
            email = request.form.get("email")
            username = request.form.get("username")
            password = request.form.get("password")
            confirmPassword  = request.form.get("confirm-password")

            with sqlite3.connect("./database") as connection:
                print("Opened database successfully")
                current = connection.cursor()

                # Ensure email was submitted
                if not email:
                    return flash("must provide email")
                # Ensure username was submitted
                if not username:
                    return flash("must provide username")

                # Ensure password was submitted
                if not password:
                    return flash("must provide password")

                # Ensure confirm password is correct
                if password != confirmPassword:
                    return flash("The passwords don't match")

                # Query database for username if already exists
                current.execute("SELECT * FROM users WHERE username = :username", username=username)
                if current.fetchall() == username: 
                    return flash("Username already taken")

                # Insert user and hash of the password into the table
                current.execute("INSERT INTO users(username, hash) VALUES (:username, :hash)", username=username, hash=generate_password_hash(password))
                current.commit()

                # Query database for username
                current.execute("SELECT * FROM users WHERE username = :username", username=username)
                rows = current.fetchall()

                # Remember which user has logged in
                session["user_id"] = rows[0]["id"]

                # Commit to databse
                connection.commit()

                print("Database operation succesful")
            
        except:
            connection.rollback()
            print("Error in sign up operation")
        
        finally:
            # Close database connection
            connection.close()
            # Redirect user to home page
            return redirect("/")

    # User reached route via GET (as by clicking a link or via redirect)
    else:
        return render_template("signup.html")

вот мой signup.html

{% extends "layout.html" %}

{% block title %}
    Sign Up
{% endblock %}

{% block main %}
    <p>Register or <a href='/signin'>login</a></p><br>
    <form action = "/signup" method = "post">
        <div>
            <p>Username (6 characters min).</p>
            <input id = "username" autocomplete = "off" autofocus class = "form-control" name = "username" placeholder = "Username" type = "text">
        </div>
        <br>
        <div>
            <p>Email.</p>
            <input id = "email" autocomplete = "off" autofocus class = "form-control" name = "email" placeholder = "Email" type = "text">
        </div>
        <br>
        <div>
            <p>Password (7 to 15 characters, 1 numeric, 1 special).</p>
            <input id = "password" name = "password" placeholder = "Password" type = "password">
        </div>
        <div>
            <input id = "confirm-pass" name = "confirm-password" placeholder = "Confirm Password" type = "password">
        </div>
        <br>
        <button id = "submit" type = "submit">Sign Up</button>
        <br>
    </form>

    <script>
        // Password must be between 7 to 15 characters which contain at least one numeric digit and a special character
        document.querySelector("#submit").disabled = true;

        document.querySelector("#confirm-pass").onkeyup = function() {
            let password = document.querySelector("#password").value;
            let username = document.querySelector("#username").value;
            let email = document.querySelector("#email").value;
            let confirmation = document.querySelector("#confirm-pass").value;

            if (password.match(/^^(?=.*[0-9])(?=.*[!@#$%^&*])[a-zA-Z0-9!@#$%^&*]{7,15}$/i)) {
                document.querySelector("#submit").disabled = true;
                if (email.match(/^(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i)) {
                    document.querySelector("#submit").disabled = true;
                    if (username.length > 5) {
                        document.querySelector("#submit").disabled = true;
                        if (confirmation === password) {
                            document.querySelector("#submit").disabled = false;
                        }
                    }
                }
            }
            else {
                document.querySelector('#submit').disabled = true;
            }
        }
    </script>
{% endblock %}

Вот вывод моей консоли:

* Serving Flask app "application.py"
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [13/Dec/2020 19:23:44] "GET /signup HTTP/1.1" 200 -
127.0.0.1 - - [13/Dec/2020 19:23:44] "GET /static/styles.css HTTP/1.1" 200 -
Opened database successfully
Error in sign up operation

Значит проблема в signup.py