从 Django 中的 JsonResponse 中提取字段值并将其传递给 Ajax Jquery答案

【问题标题】：Extracting a field value from JsonResponse in Django and pass it to Ajax Jquery从 Django 中的 JsonResponse 中提取字段值并将其传递给 Ajax Jquery
【发布时间】：2021-11-19 14:53:33
【问题描述】：

我正在 Django 中使用 ajax 和 Jquery 创建一个下拉列表选择预期的行为是当我选择第一个选择时，ajax 将填充第二个这是我暂时拥有的：

models.py

class MaintenanceEquipment(models.Model):
    equip_id = models.CharField(max_length=30, auto_created=False, primary_key=True)
    line_nm = models.CharField(max_length=20, blank=True, null = True)
    sequence = models.CharField(max_length=30, blank=True, null = True)
    equip_model = models.CharField(max_length=30, blank=True, null = True)

    def __str__(self):
    return self.equip_id

views.py：

def maintenanceIssueView(request):
    equipment_list = MaintenanceEquipment.objects.all()    
    context = {'equipment_list':equipment_list}
    return render(request, 'maintenance/maintenanceIssue.html', context)

def load_equipment(request):
    from django.core import serializers
    if request.method == 'GET':
        line_nm = request.GET.get('line_nm')
        equipment = MaintenanceEquipment.objects.filter(line_nm=line_nm)
        instances = serializers.serialize('json', equipment)
        print(instances) 
        return HttpResponse(instances, content_type='application/json')

urls.py:

urlpatterns = [
    path('maintenanceIssueView/', views.maintenanceIssueView, name="maintenanceIssueView"),      
    path('ajax/load_equipment/', views.load_equipment, name="ajax_load_equipment"),    
    ]

maintenanceIssue.html：

<form method="POST" id="maintenanceForm" data-equipment-url="{% url 'ajax_load_equipment' %}" novalidate>
    {% csrf_token %}      
    <div style="text-align:left;" class="container-fluid">    
       <div style="text-align:left;" class="form-row">
        <div class="form-group col-md-6">
            <label for="line_nm" style="font-size:medium;">Line</label>
            <select class="form-control" id="line_nm" name="line_nm" >
                {% for instance in equipment_list %}
                <option id="{{ instance.line_nm }}" value="{{ instance.line_nm }}">{{ instance.line_nm }}</option>
                {% endfor %}
            </select>
      </div>
           <div class="form-group col-md-6">
            <label for="sequence" style="font-size:medium;">Machine</label>
            <select class="form-control" id="sequence" name="sequence"></select>
           </div>
        </div>
      </div>
</form>
    
<script>
$("#line_nm").change(function () {
    var url = $("#maintenanceForm").attr("data-equipment-url");
    var line_nm = $(this).val();
    $.ajax({
            url: url,
            data: {
              'line_nm': line_nm
            },
            success: function (response) {
              // this function executes on receiving a successful response from the backend:
              var secondSelect = $('#sequence');
              secondSelect.empty();
        
               for (var instance in response.instances) {
                secondSelect.append($('<option>', {
                  value : instance.sequence,
                  text : instance.sequence
                }));
              }
            }
          });
        });
</script>

问题是：当我在终端中打印视图的输出时，我有：

[{"model": "maintenance.maintenanceequipment", "pk": 4,  
"fields":
{"equip_id": "Q230-095504-003", "mfg_part_code": "P12122", "line_nm":
"PBA-02", "sequence": "LOADER", "equip_model": "FML-400BAI-HE-SV"}},
{"model": "maintenance.maintenanceequipment", "pk": 5,  
"fields":
{"equip_id": "Q230-108839-001", "mfg_part_code": "P12122", "line_nm":
"PBA-02", "sequence": "C-MOUNTER1", "equip_model": "MAI-H8"}}]

如何在我的 ajax 中恢复它以填充第二个选择？我需要的唯一数据是 "fields": sequence

预期值：装载机、C-MOUNTER1

当前出现在 select 中的值是：0, 1, 2, 3, 4, 5, 6, 7 ....也许是一个字符串计数

如果有人可以提供帮助，我将不胜感激

【问题讨论】：

标签： python jquery django ajax

【解决方案1】：

您需要解析从服务器获得的 JSON 响应，然后遍历 JSON Array 并使用 response["instances"][i] 获取序列值[“字段”][“序列”] .

演示代码：

//this is for demo ....
var response = {
  "instances": [{
      "model": "maintenance.maintenanceequipment",
      "pk": 4,
      "fields": {
        "equip_id": "Q230-095504-003",
        "mfg_part_code": "P12122",
        "line_nm": "PBA-02",
        "sequence": "LOADER",
        "equip_model": "FML-400BAI-HE-SV"
      }
    },
    {
      "model": "maintenance.maintenanceequipment",
      "pk": 5,
      "fields": {
        "equip_id": "Q230-108839-001",
        "mfg_part_code": "P12122",
        "line_nm": "PBA-02",
        "sequence": "C-MOUNTER1",
        "equip_model": "MAI-H8"
      }
    }
  ]
}
/*$("#line_nm").change(function () {
    var url = $("#maintenanceForm").attr("data-equipment-url");
    var line_nm = $(this).val();
    $.ajax({
            url: url,
            data: {
              'line_nm': line_nm
            },
            dataType :'json', //add this....///
            success: function (response) { */
var secondSelect = $('#sequence');
secondSelect.empty();

          //loop thorugh json response //is its json object > json array use : response.instances
          for (var i = 0; i < response.instances.length; i++) {
            secondSelect.append($('<option>', {
              value: response["instances"][i]["fields"]["sequence"], //get the sequence
              text: response["instances"][i]["fields"]["sequence"]
            }));
          }
/*}
});
});*/

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<select class="form-control" id="sequence" name="sequence"></select>

【讨论】：

谢谢斯瓦蒂，它确实解决了我的问题，在此之后我只需要改变我的观点，我正在使用 JsonResponse() 并将其更改为 HttpResponse()
很高兴我能帮上忙 :)

【解决方案2】：

如果你只需要序列字段，你可以用Django直接获取这个字段

equipment = MaintenanceEquipment.objects.filter(line_nm=line_nm)
equipment_sequences = [e.sequence for e in equipment]

【讨论】：