[FIXED] Django Admin: OneToOne Relation as an Inline?

Issue

I'm putting together the admin for a satchmo application. Satchmo uses OneToOne relations to extend the base Product model, and I'd like to edit it all on one page.

Is it possible to have a OneToOne relation as an Inline? If not, what is the best way to add a few fields to a given page of my admin that will eventually be saved into the OneToOne relation?

for example:

class Product(models.Model):
    name = models.CharField(max_length=100)
    ...

class MyProduct(models.Model):
    product = models.OneToOne(Product)
    ...

I tried this for my admin but it does not work, and seems to expect a Foreign Key:

class ProductInline(admin.StackedInline):
    model = Product
    fields = ('name',)

class MyProductAdmin(admin.ModelAdmin):
    inlines = (AlbumProductInline,)

admin.site.register(MyProduct, MyProductAdmin)

Which throws this error: <class 'satchmo.product.models.Product'> has no ForeignKey to <class 'my_app.models.MyProduct'>

Is the only way to do this a Custom Form?

edit: Just tried the following code to add the fields directly... also does not work:

class AlbumAdmin(admin.ModelAdmin):
    fields = ('product__name',)

Solution

It's perfectly possible to use an inline for a OneToOne relationship. However, the actual field defining the relationship has to be on the inline model, not the parent one - in just the same way as for a ForeignKey. Switch it over and it will work.

Edit after comment: you say the parent model is already registered with the admin: then unregister it and re-register.

from original.satchmo.admin import ProductAdmin

class MyProductInline(admin.StackedInline):
    model = MyProduct

class ExtendedProductAdmin(ProductAdmin):
    inlines = ProductAdmin.inlines + (MyProductInline,)

admin.site.unregister(Product)
admin.site.register(Product, ExtendedProductAdmin)

---

Update 2020 (Django 3.1.1)

This method is still working but some types has changed in new Django version since inlines in ExtendedProductAdmin should now be added as list and not tuple, like this:

class ExtendedProductAdmin(ProductAdmin):
    inlines = ProductAdmin.inlines + [MyProductInline]

Or you will get this error:

    inlines = ProductAdmin.inlines + (MyProductInline,)
TypeError: can only concatenate list (not "tuple") to list

Answered By - Daniel Roseman