@bp.route('/login', methods=('GET', 'POST'))
def login():
if request.method == 'POST':
    username = request.get_json().get('username')
    password = request.get_json().get('password')

    #return username
    db = get_db()
    error = None
    user = db.execute(
        'SELECT * FROM user WHERE username = ?', (username,)
    ).fetchone()
    #return user['id']

    if user is None:
        error = 'Incorrect username.'
    elif not check_password_hash(user['password'], password):
        error = 'Incorrect password.'

    if error is None:
        #session.clear()
        #session['user_id'] = user['id']
        return user['id']
        #return user['username']

return error