Django 相关模型未在表单提交时更新答案

【问题标题】：Django related model not updating on form submissionDjango 相关模型未在表单提交时更新
【发布时间】：2021-04-22 06:26:52
【问题描述】：

如何通过 Django 模型表单更新不存在的相关对象？

我有两个对象：Participant 和 Emergency。紧急情况是参与者的孩子，例如运行查询：participant = ParticipantInfo.objects.get(pk = prk)我可以访问emergency = participant.emergency。

我无法使用 POST 请求使用表单中的数据更新紧急情况。谁能帮助我。谢谢

为了清楚起见，这是我的 models.py。

models.py

class EmergencyInfo(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    phone_number = models.CharField(max_length=50)
    email = models.EmailField(max_length=100, blank=True, verbose_name="Emergency Contact Email")
    relationship = models.CharField(max_length=100)


class ParticipantInfo(models.Model):
    first_name = models.CharField(max_length=100)
    middle_initial = models.CharField(max_length=1, blank=True)
     emergency = models.ForeignKey(EmergencyInfo, on_delete = models.CASCADE, editable= False, null=True, blank=True)

views.py

def update_participant(request, pk):
    # this function comes after update_specific 
    if request.method == "GET":
        forms = get_participant_form_data(pk)
        context = {'forms': forms, 'pk': pk}
        return render(request, 'core/participantinfo_update_form.html', context)
     if request.method == "POST":
        return update_specific_form(request, pk)


def update_specific_form(request, pk):
    participant = ParticipantInfo.objects.get(pk = pk)
    
    # if the object didn't exist create it like normal      
    if participant.emergency is None:
        emergencyform =EmergencyForm(request.POST)
        if (emergencyform.is_valid):
            emergencyform.save()
            messages.success(request, 'saved')
            return redirect(request.path_info)
    # if the object exists, update it
    if participant.emergency is not None:
        emergencyform = EmergencyForm(request.POST, instance = participant.emergency)           
        if (emergencyform.is_valid):
            emergencyform.save()
            messages.success(request, 'saved')
            return redirect(request.path_info)

【问题讨论】：

标签： python django django-views django-forms

【解决方案1】：

您的问题似乎与is_valid 方法有关。将其替换为is_valid()。所以你的台词是：

if (emergencyform.is_valid()):
    #code

【讨论】：

帮我解决这个问题，@Sid。 stackoverflow.com/questions/67201794/…

【解决方案2】：

我找到了答案。我不仅需要调用is_valid() 而不是is_valid 但我还需要将创建的对象与其父对象联系起来：

保存新的子对象

保存父对象（更新 null 值的外键）

 *#get the existing parent object*
 participant = ParticipantInfo.objects.get(pk = pk)

 *#if no child object exists*

 if participant.emergency is None:
             emergencyform =EmergencyForm(request.POST)
             if (emergencyform.is_valid()):
                 emergency = emergencyform.save(commit=False)
                 participant.emergency  = emergency
                 emergencyform.save()
                 participant.save()
                 messages.success(request, 'saved')
                 return redirect(request.path_info)

【讨论】：