Extracting a field value from JsonResponse in Django and pass it to Ajax Jquery-CodePudding

I'm creating a dropdown list select with ajax and Jquery in Django The expected behavior is when I choose the first select, the ajax will fill the second one This is what I have for while:

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>

The problem is: When I print the output of my view in the terminal, I have:

[{"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"}}]

How to recover it in my ajax to fill the second select? The only data I need is the "fields": sequence

Expected value: LOADER, C-MOUNTER1

The value that is current appering in select is: 0, 1, 2, 3, 4, 5, 6, 7 .... Maybe a string count

I appreciate if someone can help

CodePudding user response：

You need parse JSON response which you get from server then loop through JSON Array and get the sequence value using response["instances"][i]["fields"]["sequence"] .

Demo Code:

//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>

CodePudding user response：

If you only need the sequence field, you can just get this field with Django

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