MultiValueDictKeyError when editing inline admin object - django

Question

I am designing a simple MCQ application using the ManyToOne relationship from django website, django version 1.6.1. I have an inline admin form which supposedly allows me to add / edit answers to a given question from the same changeform. However, if after saving a question with its answers once, i am unable to edit / add answers from the same form and get a MultiValueDictKeyError. My models are:
class SBA (models.Model):
question = models.TextField(blank=False)
system = models.CharField(max_length=3, choices=pacscon.System.which_system)
case = models.ForeignKey('pacscon.Patient')
created = models.DateField(auto_now_add=True)
reference = models.TextField(blank=True)
def __unicode__(self):
return self.question
class Answer(models.Model):
id = models.AutoField(primary_key=True)
body = models.TextField()
correct = models.BooleanField(default=False)
sba = models.ForeignKey(SBA, null=True)
def __unicode__(self):
return self.body
the admin.py looks like this :
from models import Answer, SBA, Mnemonic
#from django import forms
from django.contrib import admin
class AnswerInline(admin.StackedInline):
model = Answer
extra = 2
class SBAAdmin(admin.ModelAdmin):
fieldsets = (
(None, {
'fields': ('question', 'system', 'case', 'reference')
}),
)
inlines = [
AnswerInline,
]
readonly_fields = ('created',)
admin.site.register(SBA, SBAAdmin)
admin.site.register(Answer)
admin.site.register(Mnemonic)
And the error message is :
MultiValueDictKeyError at /admin/knowledge/sba/1/
Traceback:
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
114. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in wrapper
432. return self.admin_site.admin_view(view)(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view
99. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/views/decorators/cache.py" in _wrapped_view_func
52. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/sites.py" in inner
198. return view(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapper
29. return bound_func(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view
99. response = view_func(request, *args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in bound_func
25. return func(self, *args2, **kwargs2)
File "/usr/local/lib/python2.7/dist-packages/django/db/transaction.py" in inner
339. return func(*args, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in change_view
1229. if all_valid(formsets) and form_validated:
File "/usr/local/lib/python2.7/dist-packages/django/forms/formsets.py" in all_valid
415. if not formset.is_valid():
File "/usr/local/lib/python2.7/dist-packages/django/forms/formsets.py" in is_valid
292. err = self.errors
File "/usr/local/lib/python2.7/dist-packages/django/forms/formsets.py" in errors
267. self.full_clean()
File "/usr/local/lib/python2.7/dist-packages/django/forms/formsets.py" in full_clean
314. form = self.forms[i]
File "/usr/local/lib/python2.7/dist-packages/django/utils/functional.py" in __get__
49. res = instance.__dict__[self.func.__name__] = self.func(instance)
File "/usr/local/lib/python2.7/dist-packages/django/forms/formsets.py" in forms
133. forms = [self._construct_form(i) for i in xrange(self.total_form_count())]
File "/usr/local/lib/python2.7/dist-packages/django/forms/models.py" in _construct_form
848. form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs)
File "/usr/local/lib/python2.7/dist-packages/django/forms/models.py" in _construct_form
564. pk = self.data[pk_key]
File "/usr/local/lib/python2.7/dist-packages/django/utils/datastructures.py" in __getitem__
301. raise MultiValueDictKeyError(repr(key))
Exception Type: MultiValueDictKeyError at /admin/knowledge/sba/1/
Exception Value: "u'answer_set-0-id'"
I have searched similar requests on google and stackoverflow and my django package is fully upto date (including admin inline templates as suggested in some other answers). Will appreciate any help. Thanks
P.S This is almost certainly a bug because I can replicate the problem on official django "Polls" tutorial which uses a similar ManyToOne relationship model.

Answer 1

In Django <= 1.7.3, I needed to change the primary key field of my model to AutoField:
wrong:
class Answer(models.Model):
id = IntegerField(primary_key=True)
correct:
class Answer(models.Model):
id = AutoField(primary_key=True)
See
https://code.djangoproject.com/ticket/15665

Answer 2

I have similar issue which was solved by update django-grappelli. If you did not use it, check your packages maybe you find what can affect work of admin site.
pip freeze | grep django- will show you current packages with versions

Answer 3

This answer https://stackoverflow.com/a/20246225/554807 has the explanation.
The best fix is actually to get silverfix's branch of nested-inlines: https://github.com/silverfix/django-nested-inlines
This has the fix mentioned in that answer, and others.

Answer 4

After migrating an application from Django==1.4.20 to Django==1.8.3 i had an outdated templates_django/admin/edit_inline/stacked.html and templates_django/admin/edit_inline/tabular.html files.
So i have just removed them and everything works fine now.
You can also upgrade them to your current django version instead of deleting.