Django Inline formset没有删除没有pk的中间模型？

Question

我已经从 accepted answer 实现了一个内联表单集

我在保存表单集时遇到问题，即它不会删除记录

我们可以追溯到formsets save method：

def form_valid(self, form):
            '''Handle saving of the project membership formset
            '''
            context = self.get_context_data()
            project_memberships = context['projectmembership_formset']
            if project_memberships.is_valid():
                self.object = form.save()
                project_memberships.instance = self.object
                project_memberships.save()

如果我们更深入地了解save 方法，我们会得到：

def save_existing_objects(self, commit=True):
        self.changed_objects = []
        self.deleted_objects = []
        if not self.initial_forms:
            return []

        saved_instances = []
        forms_to_delete = self.deleted_forms
        for form in self.initial_forms:
            obj = form.instance
            # If the pk is None, it means either:
            # 1. The object is an unexpected empty model, created by invalid
            #    POST data such as an object outside the formset's queryset.
            # 2. The object was already deleted from the database.
            if obj.pk is None:
                continue
            if form in forms_to_delete:
                self.deleted_objects.append(obj)
                self.delete_existing(obj, commit=commit)
            elif form.has_changed():
                self.changed_objects.append((obj, form.changed_data))
                saved_instances.append(self.save_existing(form, obj, commit=commit))
                if not commit:
                    self.saved_forms.append(form)
        return saved_instances

我发现obj 的pk 是空的，因此不会发生任何删除。

POST数据：

'projectmembership_set-0-id': [
    '8'
  ],
  'projectmembership_set-0-user': [
    '1'
  ],
  'projectmembership_set-0-is_project_manager': [
    'on'
  ],
  'projectmembership_set-0-full_time_equivalent': [
    '100.00'
  ],
  'projectmembership_set-0-DELETE': [
    'on'
  ],
  'projectmembership_set-1-id': [
    '9'
  ],
  'projectmembership_set-1-user': [
    '3'
  ],
  'projectmembership_set-1-is_project_manager': [
    'on'
  ],
  'projectmembership_set-1-full_time_equivalent': [
    '100.00'
  ],
  'projectmembership_set-1-DELETE': [
    'on'
  ],
  'projectmembership_set-2-id': [
    '10'
  ],
  'projectmembership_set-2-user': [
    '7'
  ],
  'projectmembership_set-2-full_time_equivalent': [
    '50.00'
  ],
  'projectmembership_set-2-DELETE': [
    'on'
  ],

为什么对象没有pk 并且没有被删除？

Answer 1

基于Class based viewINline formset的答案

get_context_data 和 POSTdata 在UpdateView 中也需要提供一个实例。

if self.request.POST:
            context['projectmembership_formset'] = ProjectMembershipFormSet(
                self.request.POST,
                instance=self.object
            )