def login(): if current_user.is_authenticated: return redirect(url_for('index')) form = LoginForm() form.username(style='color:red') if form.validate_on_submit(): user = User.query.filter_by(username=form.username.data).first() if user is None or not user.check_password(form.password.data): flash("Invalid username or password") return redirect(url_for('login')) login_user(user, remember=form.remember_me.data) next_page = request.args.get('next') if next_page is None or url_parse(next_page).netloc != '': next_page = url_for('index') return redirect((next_page)) return render_template('login.html', form=form, title="Sign In")