强制手动刷新留言板帖子，导致帖子重复

Question

我在MongoDB上使用烧瓶，我在app.py中有一个名为/ announcements的路由，此公告的作用类似于留言板，用户可以在其中张贴消息，并且用户可以阅读这些消息。这有一些警告。

首先，我看到用户消息正在存储在我的数据库（即MongoDB）中，但是当用户单击表单上的“提交”按钮时，页面似乎已刷新，但我不相信这确实是我通常必须要做的手动刷新页面，然后我将在页面上看到用户消息发布。

第二个问题是当我手动刷新页面时，在创建的留言板上看到同一用户帖子的重复条目。最初，我只会看到一个帖子，但是随着发布的帖子越多，刷新页面越多，重复的次数就越多。

app.py中的公告路线

# Announcements
@app.route('/announcements', methods=['GET', 'POST'])
@login_required
def announcements():

    # get current user
    for cur_user in User.objects:
        cur_user = cur_user.username

    # msg title info from db
    msg_title_list = []
    for msg_title in Announcement.objects.order_by('-pub_date'):
        msg_title = msg_title.title
        msg_title_list.append(msg_title)

    # get msg text from db
    msg_text_list = []
    for msg_text in Announcement.objects.order_by('-pub_date'):
        msg_text = msg_text.text
        msg_text_list.append(msg_text)

    # get msg date from db
    pub_date_list = []
    for pub_date in Announcement.objects.order_by('-pub_date'):
        pub_date = pub_date.pub_date
        pub_date_list.append(pub_date)

    # get username from db
    user_name_list = []
    for username in Announcement.objects.order_by('-pub_date'):
        username = username.username
        user_name_list.append(username)


    if request.method == 'POST':

        # get form data
        message_title = request.form['message_title']
        message_text = request.form['message_text']

        # push msg info into db
        Announcement(username=cur_user, title=message_title, text=message_text).save()

    return render_template('announcements.html', cur_user=cur_user, msg_data=zip(msg_title_list, 
                                                                                 msg_text_list, 
                                                                                 pub_date_list,
                                                                                 user_name_list))

announcements.html和表单数据

                                <div class="content-list-body">
                                    {% for msg_title_list, msg_text_list, pub_date_list, user_name_list in msg_data%}

                                    <div class="card card-note">
                                        <div class="card-header">
                                            <div class="media align-items-center">
                                                <img alt="Peggy Brown" src="static/img/avatar-female-2.jpg" class="avatar" data-toggle="tooltip" data-title="{{user_name_list}}" data-filter-by="alt" />
                                                <div class="media-body">

                                                    <h6 class="mb-0" data-filter-by="text">{{msg_title_list}}</h6>

                                                </div>
                                            </div>
                                            <div class="d-flex align-items-center">
                                                <span data-filter-by="text">{{pub_date_list}}</span>
                                                <div class="ml-1 dropdown card-options">
                                                    <button class="btn-options" type="button" id="note-dropdown-button-1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                                                        <i class="material-icons">more_vert</i>
                                                    </button>
                                                    <div class="dropdown-menu dropdown-menu-right">
                                                        <a class="dropdown-item" href="#">Edit</a>
                                                        <a class="dropdown-item text-danger" href="#">Delete</a>
                                                    </div>
                                                </div>
                                            </div>
                                        </div>
                                        <div class="card-body" data-filter-by="text">
                                            <p>{{msg_text_list}}</p>
                                        </div>
                                    </div>
                                    {% endfor %}
                                </div>