Django中提示消息messages的设置方式

from django.contrib import messages

@csrf_exemptdef search(request):  if request.method == 'GET':    bookname = request.GET.get('bookname')    bookinfo = Book.objects.filter(bookname=bookname)    is_staff = request.user.is_staff    username = request.user.username    gonggao = Gonggao.objects.all().order_by("-c_time")    liuyanban_all = liuyan.objects.all().order_by("-c_time")    c2 = JieInfo.objects.filter(u_name=username, book_name=bookname)    c3 = JieInfo.objects.filter(u_name=username).count()    if username == '':      messages.error(request, '亲，请您先登录,才能使用该功能。')      return redirect('/')    else:      if bookname == '':        messages.error(request, '亲，搜索内容不能为空哦。')        return redirect('/')      elif c2.exists():        messages.error(request, '对不起，您不能再次借阅该图书了。')        return redirect('/')      elif c3 == 5:        messages.error(request, '对不起，您将超出图书馆借阅图书数量限制。')        return redirect('/')      else:        if bookinfo.exists():          return render(request, "systeam/searched.html",                 {'bookinfo': bookinfo, 'username': username, 'is_staff': is_staff})        else:          messages.error(request, '亲，没有这本书呢。')          return redirect('/')  else:    return render(request, "systeam/searched.html", {'username': username})

{% if messages %}  <ul class="messages">  {% for message in messages %}    <li{%if message.tags %} class="{{ message.tags }}"{% endif %}>      <div class="m_title">        {{ message.tags }}        <a href="" id=" rel="external nofollow" rel="external nofollow" a_tuichu">          <i class="iconfont icon-fork"></i>        </a>      </div>      <div id="m_box">        {{ message }}      </div>      <a href="" id=" rel="external nofollow" rel="external nofollow" a_sure">        <button id="button_sure">        确认        </button>      </a>    </li>  {% endfor %}  </ul>  {% endif %}