Django：在新的 linline 对象中访问父对象

Question

我已经在互联网上梳理了很长一段时间，但没有找到任何解决此问题的方法。

我正在尝试做什么......

我有以下型号：

class TrackingEventType(models.Model):
    required_previous_event = models.ForeignKey(TrackingEventType)

class TrackingEvent(models.Model):
    tracking = models.ForeignKey(Tracking)

class Tracking(models.Model):
    last_event = models.ForeignKey(TrackingEvent)

现在主要模型是 Tracking，所以我的 Tracking 管理员看起来像这样：

class TrackingEventInline(admin.TabularInline):
    model = TrackingEvent
    extra = 0

class TrackingAdmin(admin.ModelAdmin):
    inlines = [TrackingEventInline]

这就是当前的设置。

现在我的任务：

在 TrackingAdmin 中，当我添加新的 TrackingEvent 内联时，我想将 TrackingEventType 的选项限制为仅允许跟随跟踪的最后一个 TrackingEvent 的选项。 （Tracking.last_event == TrackingEventType.required_previous_event）。

为此，我需要能够访问 InlineTrackingEvent 上的相关跟踪，以访问 last_event 并相应地过滤 TrackingEventType 的选项。

所以我发现了这个：Accessing parent model instance from modelform of admin inline，但是当我相应地设置 TrackingEventInline 时：

class MyFormSet(forms.BaseInlineFormSet):
    def _construct_form(self, i, **kwargs):
        kwargs['parent_object'] = self.instance
        print self.instance
        return super(MyFormSet, self)._construct_form(i, **kwargs)


class MyForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        print kwargs
        self.parent_object = kwargs.pop('parent_object')
        super(MyForm, self).__init__(*args, **kwargs)

class TrackingEventInline(admin.TabularInline):
    form = MyForm
    formset = MyFormSet

    model = TrackingEvent
    extra = 0

我从self.parent_object = kwargs.pop('parent_object') 得到一个KeyError at /admin/.../tracking/2/change/ 'parent_object'

---

有谁知道如何解决这个问题？我是否以错误的方式解决问题？我想这在前端的自定义表单中会很容易，但我真的很想使用管理员，因为整个应用程序都是为管理员使用而构建的，构建自定义的工作量很大管理界面只是因为这个问题:)

Answer 1

好的，所以在 StackOverflow 上发帖总是有助于解决问题。我能够制定出适合我的解决方案。

它包括在外部函数中定义我自己的表单，以及为 TrackingEvent 定义两个 InlineAdmin 对象（一个用于更新/编辑，一个仅用于插入）。

代码如下：

def create_trackingevent_form(tracking):
    """
    """
    class TrackingEventForm(forms.ModelForm):
        """
        Form for Tracking Event Inline
        """

        def clean(self):
            """
            May not be needed anymore, since event type choices are limited when creating new event.
            """
            next_eventtype = self.cleaned_data['event_type']
            tracking = self.cleaned_data['tracking']
            # get last event, this also ensures last_event gets updated everytime the change form for TrackingEvent is loaded
            last_eventtype = tracking.set_last_event()

            if last_eventtype:
                last_eventtype = last_eventtype.event_type

            pk = self.instance.pk
            insert = pk == None
            # check if the event is updated or newly created
            if insert:
                if next_eventtype.required_previous_event == last_eventtype:
                    pass
                else:
                    raise forms.ValidationError('"{}" requires "{}" as last event, "{}" found. Possible next events: {}'.format(
                        next_eventtype, 
                        next_eventtype.required_previous_event, 
                        last_eventtype,
                        '"%s" ' % ', '.join(map(str, [x.name for x in  tracking.next_tracking_eventtype_options()]))
                        )
                    )
            else:
                pass
            return self.cleaned_data

        def __init__(self, *args, **kwargs):
            # You can use the outer function's 'tracking' here
            self.parent_object = tracking

            super(TrackingEventForm, self).__init__(*args, **kwargs)
            self.fields['event_type'].queryset = tracking.next_tracking_eventtype_options()
            #self.fields['event_type'].limit_choices_to = tracking.next_tracking_eventtype_options()

    return TrackingEventForm


class TrackingEventInline(admin.TabularInline):
    #form = MyForm
    #formset = MyFormSet

    model = TrackingEvent
    extra = 0

    #readonly_fields = ['datetime', 'event_type', 'note']

    def has_add_permission(self, request):
        return False



class AddTrackingEventInline(admin.TabularInline):
    model = TrackingEvent
    extra = 0

    def has_change_permission(self, request, obj=None):
        return False

    def queryset(self, request): 
        return super(AddTrackingEventInline, self).queryset(request).none()

    def get_formset(self, request, obj=None, **kwargs):
        if obj:
            self.form = create_trackingevent_form(obj)
        return super(AddTrackingEventInline, self).get_formset(request, obj, **kwargs)

我希望这可以帮助其他有同样问题的人。感谢 Stack Overflow 线程帮助我提出这个问题：

Prepopulating inlines based on the parent model in the Django Admin

Limit foreign key choices in select in an inline form in admin

https://docs.djangoproject.com/en/1.9/ref/models/instances/#django.db.models.Model.clean_fields

如果您有任何问题，请随时提出问题