InlineAdminForm breaks content_type FK on model
|Reported by:||Carl Meyer||Owned by:||Carl Meyer|
|Cc:||Robin Breathe, Robert||Triage Stage:||Accepted|
|Has patch:||yes||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
r8586 fixed "View on Site" links for admin inline formsets, by having
InlineAdminForm.__init__ set a temporary "content_type_id" attribute on the inline-edited "original" instance to the content type id of its model, and then using that attribute in the template to link to the redirection.
This is all fine and dandy, except when the model being edited inline already has a "content_type" field which is a foreign key to ContentType (most likely because it has a generic foreign key). In this case, InlineAdminForm reassigns an already-existing "content_type_id" attribute to point to the wrong model entirely, breaking any behavior of the instance that depends on the generic foreign key.
This behavior can be seen with these test models:
from django.db import models from django.contrib.contenttypes.models import ContentType from django.contrib.contenttypes import generic class Parent(models.Model): name = models.CharField(max_length=50) def __unicode__(self): return self.name class Teacher(models.Model): name = models.CharField(max_length=50) def __unicode__(self): return self.name class Child(models.Model): name = models.CharField(max_length=50) teacher = models.ForeignKey(Teacher) content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() parent = generic.GenericForeignKey() def __unicode__(self): return u'I am %s, a child of %s' % (self.name, self.parent)
With this admin configuration:
from django.contrib import admin from models import Child, Teacher, Parent class ChildInline(admin.TabularInline): model = Child extra = 1 class TeacherAdmin(admin.ModelAdmin): inlines = (ChildInline,) admin.site.register(Teacher, TeacherAdmin) admin.site.register(Parent)
In the admin, create a Parent named John, then create a Teacher named Sally, then add a Child named Joe using the inline formset for the Teacher. After saving the Child, where the new Child's unicode representation should be displayed as "I am Joe, a child of John", it will instead say "I am Joe, a child of I am Joe, a child of John". This is because InlineAdminForm has changed Joe's content_type_id from Parent to Child, so Joe's "parent" attribute is now pointing to himself.
(The reason for the Teacher model and FK in the above examples is to make it clear that this occurs with any ordinary InlineAdmin, not only with a GenericInlineAdmin).
The easy fix is to use a more obscure attribute name for the temporary "my content type" attribute needed for redirection. Technically it would still be possible to mistakenly overwrite an existing attribute, but much less likely than it is now.
Change History (14)
comment:1 Changed 8 years ago by
|Patch needs improvement:||unset|
comment:2 Changed 8 years ago by
|Owner:||changed from nobody to Brian Rosner|
|Status:||new → assigned|
|Triage Stage:||Unreviewed → Accepted|
comment:7 Changed 8 years ago by
|Owner:||changed from Brian Rosner to Carl Meyer|
|Status:||assigned → new|