如何让我的注册函数自动登录(HTML、Flask、Python)

<form action="/register" method="POST">
  <label for="username">用户名:</label>
  <input type="text" id="username" name="username"><br><br>
  <label for="password">密码:</label>
  <input type="password" id="password" name="password"><br><br>
  <input type="submit" value="注册">
</form>

from flask import Flask, render_template, request, redirect, session
from werkzeug.security import generate_password_hash, check_password_hash

app = Flask(__name__)
app.secret_key = 'your_secret_key'

@app.route('/register', methods=['POST'])
def register():
    username = request.form['username']
    password = request.form['password']
    hashed_password = generate_password_hash(password)
    
    # 将用户名和哈希后的密码保存到数据库中
    
    # 注册成功后进行自动登录
    session['username'] = username
    
    return redirect('/dashboard')  # 注册成功后重定向到用户仪表盘页面

@app.route('/dashboard')
def dashboard():
    if 'username' in session:
        # 用户已登录，显示用户仪表盘页面
        return render_template('dashboard.html', username=session['username'])
    else:
        # 用户未登录，重定向到登录页面
        return redirect('/login')

{% if username %}
  <h1>欢迎, {{ username }}!</h1>
{% else %}
  <h1>请先登录</h1>
{% endif %}