使用外键集编辑站点设置时生成 KeyError

Question

Django 版本：2.1.5

Python版本：3.6.8

鹡鸰版本： 2.4

我有一个模板，其页脚中有四列 link。我已经为 link 的每一列设置了以下模型，其中包含一个 BaseSetting 对象和页脚 link 对象。页脚 link 对象每个 ForeignKey 到 TemplateItems 对象。

@register_setting
class TemplateItems(BaseSetting):
    page_banner = models.OneToOneField('wagtailimages.Image', null=True, blank=True, on_delete=models.SET_NULL, related_name='+',  help_text='Banner image that shows below menu on pages other than home page')
    footer_link_col1_header = models.CharField(max_length=25, default='', verbose_name='Footer Link Column 1 Header')
    footer_link_col2_header = models.CharField(max_length=25, blank=True, default='', verbose_name='Footer Link Column 2 Header')
    footer_link_col3_header = models.CharField(max_length=25, blank=True, default='', verbose_name='Footer Link Column 3 Header')
    footer_link_col4_header = models.CharField(max_length=25, blank=True, default='', verbose_name='Footer Link Column 4 Header')

    panels = [
        ImageChooserPanel('page_banner'),
        MultiFieldPanel([
            FieldPanel('footer_link_col1_header'),
            InlinePanel('footer_links_col_1', label='Column 1 Links'),
            FieldPanel('footer_link_col2_header'),
            InlinePanel('footer_links_col_2', label='Column 2 Links'),
            FieldPanel('footer_link_col3_header'),
            InlinePanel('footer_links_col_3', label='Column 3 Links'),
            FieldPanel('footer_link_col4_header'),
            InlinePanel('footer_links_col_4', label='Column 4 Links'),
        ], heading='Footer Links'),
        InlinePanel('social_media_links', label="Social Media Links"),
    ]


class FooterLink(Orderable):
    name = models.CharField(max_length=60, default='')
    url = models.CharField(max_length=200, default='')

    panels = [
        FieldRowPanel([
            FieldPanel('name'),
            FieldPanel('url'),
        ])
    ]

    class Meta:
        abstract = True

    def __str__(self):
        return f'{self.name}'


class FooterLinkCol1(FooterLink):
    template_items = ForeignKey('TemplateItems', related_name='footer_links_col_1', null=True, on_delete=models.SET_NULL)


class FooterLinkCol2(FooterLink):
    template_items = ForeignKey('TemplateItems', related_name='footer_links_col_2', null=True, on_delete=models.SET_NULL)


class FooterLinkCol3(FooterLink):
    template_items = ForeignKey('TemplateItems', related_name='footer_links_col_3', null=True, on_delete=models.SET_NULL)


class FooterLinkCol4(FooterLink):
    template_items = ForeignKey('TemplateItems', related_name='footer_links_col_4', null=True, on_delete=models.SET_NULL)

迁移已成功创建和迁移，但是当我转到 Wagtail 管理中的 TemplateItems 设置对象以添加页脚 links 时，我收到以下错误：

KeyError at /admin/settings/main/templateitems/2/

'footer_links_col_1'

如果我注释掉任何 footer_links_col_X 项，那么我会收到第一个未注释掉的错误。数据库中没有任何列的现有页脚 link。我想知道问题是不是因为 ForeignKey 是 BaseSetting 对象，但是当我在 Django 管理中声明这些模型时（包括每个列的内联 links），它显示并允许我添加 links 就好了。

回溯：

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner 34. response = get_response(request)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response 126. response = self.process_exception_by_middleware(e, request)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response 124. response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/django/views/decorators/cache.py" in _wrapped_view_func 44. response = view_func(request, *args, **kwargs)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/urls/init.py" in wrapper 102. return view_func(request, *args, **kwargs)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/decorators.py" in decorated_view 34. return view_func(request, *args, **kwargs)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/contrib/settings/views.py" in edit 83. instance=instance, form=form, request=request)

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in bind_to_instance 153. new.on_instance_bound()

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in on_instance_bound 295. request=self.request))

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in bind_to_instance 153. new.on_instance_bound()

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in on_instance_bound 295. request=self.request))

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in bind_to_instance 153. new.on_instance_bound()

File "/opt/virtualenvs/MY_SITE-a0hNfZxl/lib/python3.6/site-packages/wagtail/admin/edit_handlers.py" in on_instance_bound 692. self.formset = self.form.formsets[self.relation_name]

Exception Type: KeyError at /admin/settings/main/templateitems/2/ Exception Value: 'footer_links_col_1'

Answer 1

InlinePanel要求对应的外键是ParentalKey:

from modelcluster.fields import ParentalKey

class FooterLinkCol1(FooterLink):
    template_items = ParentalKey('TemplateItems', related_name='footer_links_col_1', null=True, on_delete=models.SET_NULL)

反过来，ParentalKey 要求父模型继承自 ClusterableModel（对于 Wagtail Page 模型自动成立）：

from modelcluster.models import ClusterableModel

class TemplateItems(BaseSetting, ClusterableModel):

（在 the readme for django-modelcluster 中对 ClusterableModel / ParentalKey 的动机做了一些解释。）

使用外键集编辑站点设置时生成 KeyError

KeyError generated when editing site setting with foreign key set

wagtail