Django Formset management-form validation error

Question

I have a form and a formset on my template. The problem is that the formset is throwing validation error claiming that the management form is \"missing or has been tampered

Answer 1

I have figured this out after running into the same error. In situations where you are using a form and a formset in the same view and template, the form should be processed before the formset to avoid raising a formset validation error.

of importance Also, if request.method == 'POST': SHOULD ONLY be used on the formset. So the above will appear as below in the view:

@login_required
def home(request):

    user = UserProfile.objects.get(pk=request.session['_auth_user_id'])
    blogz = list(blog.objects.filter(deleted='0'))
    delblog = modelformset_factory(blog, exclude=('poster','date' ,'title','content')) 
    if request.user.is_staff== True:
        staff = 1
    else:
        staff = 0
    staffis = 1

    blogform = BlogForm(request.POST)
    if blogform.is_valid():
        blogform.save()
        return HttpResponseRedirect('/home')

   else:
    blogform = BlogForm(initial = {'poster':user.id})

    if request.method == 'POST':
    delblogformset = delblog(request.POST)
    if delblogformset.is_valid():
        delblogformset.save()
        return HttpResponseRedirect('/home')

    else:
        delblogformset = delblog(queryset=blog.objects.filter( deleted='0'))



    blogs= zip(blogz,delblogformset.forms)  

    paginator = Paginator(blogs, 10) # Show 25 contacts per page

    # Make sure page request is an int. If not, deliver first page.
    try:
        page = int(request.GET.get('page', '1'))
    except ValueError:
        page = 1

    # If page request (9999) is out of range, deliver last page of results.
    try:
        blogs = paginator.page(page)
    except (EmptyPage, InvalidPage):
        blogs = paginator.page(paginator.num_pages)

    return render_to_response('home.html', {'user':user, 'blogform':blogform, 'staff': staff, 'staffis': staffis, 'blog':blogs, 'delblog':delblogformset}, context_instance = RequestContext( request ))

Answer 2

To avoid this error just wrap your formset POST bounding in a try/except block like so.

from django.core.exceptions import ValidationError # add this to your imports

if request.method == 'POST':
   try:
      delblogformset = delblog(request.POST)
   except ValidationError:
      delblogformset = None
   if delblogformset and delblogformset.is_valid():
      delblogformset.save()
          return HttpResponseRedirect('/home')

The POST request from your blogform lacks the 'ManagementForm' hidden input that is required for your delblogformset and hence the validation error is thrown. We wrap in a try/except block because we know that if ValidationError has been raised than the POST was meant for your blogform and not delblogformset.

For more information see django docs: http://docs.djangoproject.com/en/dev/topics/forms/formsets/#understanding-the-managementform