hello.py

from flask import Flask, render_template, session, redirect, url_for , flash
from flask import request
from flask import Flask, render_template
from flask_bootstrap import Bootstrap
from flask_moment import Moment
from datetime import datetime
from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import Email, DataRequired, ValidationError


app = Flask(__name__)
app.config['SECRET_KEY'] = 'hard to guess string'
bootstrap = Bootstrap(app)
moment = Moment(app)

def validate_email(form, field):
    if "@" not in field.data:
        raise ValidationError(f"Please include '@' in the email address. {field.data} is missing an '@'")

class NameForm(FlaskForm):
    name = StringField('What is your name?', validators=[DataRequired()])
    email = StringField('What is your UofT email adderess?', validators=[validate_email])
    submit = SubmitField('Submit')


@app.route('/user/<name>')
def user(name):
    return render_template('index.html', name=name)


@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()
    if form.validate_on_submit():
        name = form.name.data
        email = form.email.data
        old_name = session.get('name')
        old_email = session.get('email')
        if old_name is not None and old_name != form.name.data:
            flash('Looks like you have changed your name!')
        if old_email is not None and old_email != form.email.data:
            flash('Looks like you have changed your email!')
        session['name'] = form.name.data
        session['email'] = form.email.data
        return redirect(url_for('index'))
    return render_template('index.html', form=form, name=session.get('name') , email=session.get('email'))

@app.errorhandler(404)
def page_notfound(e):
    return render_template('404.html'), 404