Testing related page in Wagtail - django

Question

I've got a ContentPage model in wagtail and a RelatedPost model that links other ContentPage models to ContentPage a bit like this:
class ContentPage(Page):
summary = RichTextField(blank=True)
body = RichTextField(blank=True)
published = models.DateTimeField(default=timezone.now())
content_panels = Page.content_panels + [
FieldPanel('summary'),
FieldPanel('body', classname="full"),
InlinePanel('related_page', label="Related Content"),
]
settings_panels = Page.settings_panels + [
FieldPanel('published'),
]
class RelatedPost(Orderable):
post = ParentalKey(
'ContentPage',
related_name='related_page'
)
page = models.ForeignKey(
'ContentPage',
null=True,
blank=True,
on_delete=models.SET_NULL,
related_name="+"
)
panels = [
FieldPanel('page')
]
When I run this test:
class ContentPageTests(WagtailPageTests):
def test_can_create_article_page(self):
self.assertCanCreateAt(ContentIndexPage, ContentPage)
# content_index is just a parent page
content_index = self.create_content_index_page()
self.assertCanCreate(content_index, ContentPage, {
'title': 'Test Article',
'published': datetime.datetime.now()
})
I get an error saying:
django.core.exceptions.ValidationError: ['ManagementForm data is missing or has been tampered with']
The admin works fine. I can save related pages etc and when I comment out the InlinePanel line it works fine.

Answer 1

The data passed to assertCanCreate needs to match the format of a form submission being posted to the 'edit page' form in the Wagtail admin. For a child model in an InlinePanel, Wagtail handles this with a Django formset - see https://docs.djangoproject.com/en/1.10/topics/forms/formsets/#formset-validation - and so you need to supply all the fields that the Django formset logic would expect, including the management form. The simplest case that passes validation is a management form that simply reports that there are no child forms:
self.assertCanCreate(content_index, ContentPage, {
'title': 'Test Article',
'published': datetime.datetime.now(),
'related_page-TOTAL_FORMS': 0,
'related_page-INITIAL_FORMS': 0,
'related_page-MAX_NUM_FORMS': 999,
})