#17871: Broken: GenericInlineModelAdmin and two ForeignKey
-------------------------------+--------------------
     Reporter:  danny.adair@…  |      Owner:  nobody
         Type:  Bug            |     Status:  new
    Component:  contrib.admin  |    Version:  1.3
     Severity:  Normal         |   Keywords:
 Triage Stage:  Unreviewed     |  Has patch:  0
Easy pickings:  1              |      UI/UX:  0
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 A scenario that I would not call exotic at all:

 models.py


 {{{
     from django.contrib.contenttypes import generic
     from django.contrib.contenttypes.models import ContentType
     from django.db import models

     class Whatever(models.Model):
         something = models.CharField(max_length=254)

     class Person(models.Model):
         name = models.CharField(max_length=254)

     class Action(models.Model):
         content_type = models.ForeignKey(ContentType)
         object_id = models.PositiveIntegerField()
         content_object = generic.GenericForeignKey('content_type',
 'object_id')

         task = models.CharField(max_length=254)
         accountable = models.ForeignKey(Person,
 related_name='actions_accountable_for', null=True, blank=True)
         assigned_to = models.ForeignKey(Person,
 related_name='actions_assigned_to', null=True, blank=True)
         due_date = models.DateField(null=True, blank=True)
         completed_date = models.DateField(null=True, blank=True)
 }}}

 So I want to attach an "Action" (something that needs to be done) to
 various other things (generic relation), and it has a Person being
 accountable and a Person that's assigned to it. They have a different
 related_name so all good.

 admin.py

 {{{
     from django.contrib import admin
     from django.contrib.contenttypes.generic import GenericStackedInline
     from models import Action, Whatever

     class ActionInline(GenericStackedInline):
         model = Action

     class WhateverAdmin(admin.ModelAdmin):
         inlines = [ActionInline]
     admin.site.register(Whatever, WhateverAdmin)
 }}}

 That throws the exception

 {{{
     <class 'myproject.myapp.models.Action'> has more than 1 ForeignKey to
 <class 'myproject.myapp.models.Person'>
 }}}

 This happens in admin.validation.validate_inline() triggered by
 "admin.site.register(Whatever, !WhateverAdmin)".

 I don't get it. The related_name are different, and the foreign key for
 the inline is a !GenericForeignKey. I thought maybe I just have to satisfy
 that (buggy?) validation and set 'fk_name' in !ActionInline to one of the
 two (as the !GenericStackedInline won't be using it anyway). But then I
 get:

 {{{
     fk_name 'accountable' is not a ForeignKey to <class
 'myproject.myapp.models.Whatever'>
 }}}

 Sure it's not. But it's not the relevant foreign key for this inline - the
 generic foreign key is. Is this a bug? How can I get around this?

 P.S.:
 The documentation states I can use a !GenericInlineModelAdmin
 https://docs.djangoproject.com/en/dev/ref/contrib/contenttypes/#generic-
 relations-in-forms-and-admin
 It also says that if an inline has two !ForeignKeys to the same model,
 "fk_name" needs to be specified
 https://docs.djangoproject.com/en/dev/ref/contrib/admin/#working-with-a
 -model-with-two-or-more-foreign-keys-to-the-same-parent-model
 That seems to assume that the two !ForeignKeys are used in the inline for
 that foreign model.

 What's also freaky is that with settings.DEBUG=True the Exception is
 thrown but with DEBUG=False the change_form is rendered without complaints
 (and seemingly working).

-- 
Ticket URL: <https://code.djangoproject.com/ticket/17871>
Django <https://code.djangoproject.com/>
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