How should I handle admin inlines for a GenericForeignKey behind a ManyToMany relation?

Question

I have a Django model which can have many generic relationships. This is achieved by manually creating a junction model:

class ContentProjectContentItem(models.Model):
    content_project = models.ForeignKey('ContentProject')

    # Generic relations via Content Type Framework
    object_id = models.PositiveIntegerField()
    content_type = models.ForeignKey(ContentType)
    item = generic.GenericForeignKey('content_type', 'object_id') 

    class Meta:
        unique_together = ('content_project', 'object_id', 'content_type')
        app_label = "cms"

That is related to the parent model via a ManyToManyField:

class ContentProject(models.Model):
    title = models.CharField(max_length=100)
    date_created = models.DateTimeField(auto_now_add=True)

    # Related content (Assets, Resources, Media, etc)
    content_items = models.ManyToManyField(ContentProjectContentItem)

I'm still developing my skills using the Django admin, so I'm unsure of how to create an inline that will allow me to add multiple ContentProjectContentItems to a ContentProject. I have tried using generic.GenericStackedInline, but to no avail:

class ContentItemInline(generic.GenericStackedInline):
    name = "content_project"
    model = ContentProjectContentItem 

class ContentProjectAdmin(MPTTModelAdmin):
    list_display = ('title' , 'date_created')
    search_fields = ('title' , 'date_created')

    inlines = [
        ContentItemInline,
    ]

I am simply seeing the standard ManyToMany multi-select for content_items (which is what I would expect). I am unsure of how to make ContentProjectAdmin aware of the junction table's generic relationships. Any thoughts?

Answer 1

I ended up implementing a custom change_view template to manually add form elements, and overrides for the form save method to handle this use case.

Not the prettiest solution, but effective nonetheless.