Django-使用AJAX来；溪流；带有注释的查询集的结果

因此，我正在加载模型字段中存在的每个值的计数。一切正常，但每次对数据库进行更改时，我都必须重新启动服务器，以使更改在前端生效

class ToggleFavouriteSignalView(View):
    def post(self, request, *args, **kwargs):
        obj_id = kwargs['signal_id']

        try:
            model_obj = CanBusLogAnalyzer.objects.get(id=obj_id)

            new_val = False if model_obj.favourite else True

            model_obj.favourite = new_val
            model_obj.save()

            response_text = 'Success:Signal setted as favourite.' if new_val else 'Info:Signal removed as favourite.'

            return HttpResponse(response_text, status=200)
        except CanBusLogAnalyzer.DoesNotExist:
            return HttpResponse('Error:The object no longer exists in the database.', status=503)
        except Exception:
            return HttpResponse('Error:Please check your internet connection.', status=503)

我认为AJAX可能适合这种情况，但我不知道怎么做。还要注意的是，在我的查询中，我有在模板中使用的注释

我的意见如下：

def counts(request):
    duplicates = Application.objects.all().filter(is_qualified="awarded").values('school_name').annotate(name_count=Count('school_name'))
    context = {
    'repeated_names' : records,
    'duplicates' : duplicates,
    'title' : 'Disbursement Details',
}

return render(request, 'calculations/list.html', context)

我的网址如下：

path('list/', default_views.counts, name='count_rows'),

最后，我的模板是：

<table class="table table-hover" id="disbursement_table">
         <thead class=" wow fadeInLeft">
            <tr>
                <th>#</th>
                <th>School</th>
                <th>Number of Applicants</th>

            </tr>
         </thead>
         <tbody class=" wow fadeInRight" wow-data-duration="2s">

            {% for application in duplicates %}

             <tr class="clickabe-row" data-target="{% url 'dup_detail' application.school_name %}">
                <td>{{ forloop.counter}}</td>
                <td>{{ application.school_name}}</td>
                <td>{{ application.name_count }}</td>
             </tr>

            {% endfor %}

         </tbody>
    </table>

#
学校
申请人数
{%用于重复的应用程序%}
{{forloop.counter}
{{申请.学校名称}
{{application.name_count}
{%endfor%}

---

是否有一种方法可以使用AJAX在每次数据库发生更改时定期更新

{{application.name\u count}}

值？

我认为您有两种选择：

使用Django的优秀Websockets库：

• ，这是本机Django功能，将允许您知道数据何时保存到模型中
• 然后，您只需要在javascript端实现Websocket通信，这相对简单

信号.py示例

@receiver(post_save, sender=CanBusAnalyzerJob, dispatch_uid='update_job_status_listeners')
def update_job_status_listeners(sender, instance, **kwargs):
    '''
    Sends job status to the browser when a Job is modified
    '''
    job_id = instance.job_id
    group_name = 'new-job-' + job_id

    message = {
        'total': instance.job_total,
        'progress': instance.progress,
        'status': instance.status
    }

    channel_layer = channels.layers.get_channel_layer()

    async_to_sync(channel_layer.group_send)(
        group_name,
        {
            'type': 'send_job_progress',
            'text': message
        }
    )

测试websocket连接的JS代码

<script>
  var socket = new WebSocket('ws://' + window.location.host + '/ws/');

  socket.onopen = function() {
    console.log("Websocket connection done!");

    if (socket.readyState == WebSocket.OPEN) {
      setInterval(function() {
        socket.send('Hello World');
      }, 10000);
    }
  };

  socket.onmessage = function(e) {
    var data = JSON.parse(e.data);
    var message = data['message'];
    console.log(data);
  };

  socket.onclose = function(e) {
    console.error('Chat socket closed unexpectedly');
  };
</script>

JS代码

//For authentication purposes
function getCrsfCookie() {
    var cookieValue = null,
        name = 'csrftoken';
    if (document.cookie && document.cookie !== '') {
        var cookies = document.cookie.split(';');
        for (var i = 0; i < cookies.length; i++) {
            var cookie = cookies[i].trim();
            if (cookie.substring(0, name.length + 1) == (name + '=')) {
                cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
                break;
            }
        }
    }
    return cookieValue;
}

//Runs every 5 seconds
setInterval(function() {
    var csrfcookie = getCrsfCookie();

    var xhttp = new XMLHttpRequest();

    xhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 503) {
            alert("Error when trying to toggle favourite!")
        }
    };

    url_arr = window.location.href.split("/")
    base_url = url_arr[0] + "//" + url_arr[2]

    var params = 'signal_id=' + signal_id;
    xhttp.open('POST', base_url + destination_url, true);
    xhttp.setRequestHeader('X-CSRFToken', csrfcookie);
    xhttp.send(params);
}, 5000);

//用于身份验证
函数getCrsfCookie（）{
var cookieValue=null，
名称='csrftoken'；
if（document.cookie&&document.cookie！=''）{
var cookies=document.cookie.split（“；”）；
对于（变量i=0；i