flask登录控制显示内容

以下是登录和登出的逻辑

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        if username == 'admin' and password == 'admin':
            session['logged_in'] = True
            session['username'] = username
            flash("登陆成功")
            return redirect(url_for('novel_index'))
        else:
            return 'Invalid username or password'
    return redirect(url_for('novel_index'))


@app.route('/logout', methods=['GET', 'POST'])
def logout():
    session.pop('logged_in', None)
    session.pop('username', None)
    return redirect(url_for('novel_index'))

在登录后设置了session会话值

session['logged_in'] = True

{% if session.logged_in %}

{% if session.logged_in %}
    <!-- 登录表单，实际上用户已经登录，所以可以显示欢迎信息或其他内容 -->
    <form class="navbar-form pull-right" action="/logout" method="post">
        <button type="submit" class="btn">Logout</button>
    </form>
{% else %}
    <!-- 登录表单 -->
    <form class="navbar-form pull-right" action="/login" method="post">
        <input class="span2" type="text" name="username" placeholder="Username">
        <input class="span2" type="password" name="password" placeholder="Password">
        <button type="submit" class="btn">Sign in</button>
    </form>
{% endif %}