Despite what django doc says, multiple inheritance with a common ancestor causes an error(models.E005). I found a tricky solution, but are there any better solutions?
Hyunsoo Kim
models.E005: The field '<common-ancestor>_ptr' from parent model '<myapp>.<parent-1>' clashes with the field '<common-ancestor>_ptr' from parent model '<myapp>.<parent-2>'.
Melvyn Sopacua
On Tuesday 13 June 2017 09:54:03 Hyunsoo Kim wrote:
> This doc
> <https://docs.djangoproject.com/en/1.11/topics/db/models/#multiple-inh
> eritance> says multiple inheritance with a common ancestor can do the
> job. However, I've experienced an error while making migrations.
> Here's the error message.
>
> > models.E005: The field '*<common-ancestor>*_ptr' from parent model '
> > *<myapp>.<parent-1>*' clashes with the field
> > '*<common-ancestor>_*ptr' from parent model '*<myapp>.<parent-2>*'.
>
> After some googling, I fount this stackoverflow Q&A
> This solves the problem by create an explicit different parent_link in
> parent model to prevent collision.
> But it seems redundant to hold two multiple ancestor link in the child
> model.
> Is there any solution with no redundant field?
Sorry, but you haven't convinced us you've implemented the common ancestor part properly. It means you have at minimum 4 models in play and none of them can be abstract.
The most common error is to mark the grandparent abstract and this copies the autofield to it's children instead of having a shared parent link.
Gotta say though, that the docs are sparse.
--
Melvyn Sopacua
Hyunsoo Kim
I don't think this is my special case problem. The same problem happens when you use the common ancestor model in the django document.