validate_form.py

# form is submitted via a POST request to the /register route
@app.route('/register', methods=['GET', 'POST'])
def register():
    # this is using a class created using WTForms
    form = RegForm()
    if request.method == 'POST':
        # form is validated via WTForms .validate() method
        if form.validate():
            # checks if submitted email has already been registered
            existing_user = User.objects(email=form.email.data).first()
            if existing_user is None:
                # the password is hashed using generate_password_hash function from werkzeug.security.
                hashpass = generate_password_hash(form.password.data, method='sha256')
                # users credentials are saved to database
                hey = User(form.email.data,hashpass).save()
                # login_user function from flask_login logs the user in
                login_user(hey)
                # user is then redirected to the dashboard route
                return redirect(url_for('dashboard'))
    return render_template('register.html', form=form)