Wagtail generic gallery implementation and OneToOneField - wagtail

Question

http://docs.wagtail.io/en/v1.13.1/getting_started/tutorial.html
The wagtail getting_started tutorial intros a blog gallery feature, implements as below:
class BlogPage(Page):
...
class BlogPageGalleryImage(Orderable)
page = ParentalKey(BlogPage, related_name='gallery_images')
image = ...
This way works, however BlogPageGalleryImage couples with BlogPage model. My intention is to make a generic gallery model which can be embbed with any model(page). The idea is using an intermediate Gallery model:
class BlogPage(Page):
gallery = models.OneToOneField(Gallery, on_delete=models.SET_NULL, null=True)
...
class Gallery(Page):
pass
class GalleryImage(Orderable):
gallery = ParentalKey(Gallery, related_name='images')
Then in code, we can get the images via blog.gallery.images.
My question is how to get it work with wagtail admin interface to inline create/edit the gallery object (OneToOneField) when editing the blog page object.

Answer 1

One way to do this is via a more generic relationship for your Page-Image connection, relating this to the Page model, rather than a specific BlogPage model.
This means that any page can have gallery images, you just need to expose the field to content panels via an InlinePanel.
You can also create a Mixin class to make some helpful methods available without rewriting them each time.
Here is an example:
from django.db import models
from wagtail.admin.edit_handlers import InlinePanel
from wagtail.core.models import Orderable, Page
from wagtail.images.edit_handlers import ImageChooserPanel
class ImageGalleryRelationship(Orderable, models.Model):
""" Relationship between any `Page` and `Image` for an image gallery."""
page = ParentalKey(Page, related_name='gallery_page')
image = models.ForeignKey('wagtailimages.Image', related_name='gallery_image')
panels = [ImageChooserPanel('image')]
class PageGalleryMixin():
def gallery_images(self):
images = [g.image for g in self.gallery_page.all()]
return images
class BlogPage(Page, PageGalleryMixin):
# all page fields, gallery does not need to be defined here
content_panels = Page.content_panels + [
InlinePanel('gallery_page', label='Image Gallery'),
#...
]
Note: This is not a OneToOne connection, InlinePanel requires a ParentalKey relationship. There is no real 'Gallery' model in this solution just a set of orderable relationships.

Answer 2

In general app (or wherever), models.py
class PageGalleryImage(Orderable):
page = ParentalKey(Page,
on_delete=models.CASCADE,
related_name='image_gallery')
image = models.ForeignKey('wagtailimages.Image',
on_delete=models.CASCADE,
related_name='page_gallery_image')
caption = models.CharField(blank=True, max_length=250)
panels = [
ImageChooserPanel('image'),
FieldPanel('caption'),
]
Other apps as blog, models.py:
class BlogPage(Page):
content_panels = Page.content_panels + [
...
InlinePanel('image_gallery', label="Gallery images"),
]
This provides one app = one gallery.