title: Django: Model Form "object has no attribute 'cleaned_data'"
body: <p>I am trying to make a search form for one of my classes. The model of the form is:</p>
  
  <pre><code>from django import forms
  from django.forms import CharField, ModelMultipleChoiceField, ModelChoiceField
  from books.models import Book, Author, Category
  
  class SearchForm(forms.ModelForm):
      authors = ModelMultipleChoiceField(queryset=Author.objects.all(),required=False)    
      category = ModelChoiceField (queryset=Category.objects.all(),required=False)
      class Meta:
          model = Book
          fields = ["title"]
  </code></pre>
  
  <p>And the view I'm using is:</p>
  
  <pre><code>from django.shortcuts import render_to_response, redirect, get_object_or_404
  from django.template import RequestContext
  from books.models import Book,Author
  from books.forms import BookForm, SearchForm
  from users.models import User
  
  def search_book(request):
      if request.method == "POST":
          form = SearchForm(request.POST)
          if form.is_valid():
              form = SearchForm(request.POST)
              stitle = form.cleaned_data['title']
              sauthor = form.cleaned_data['author']
              scategory = form.cleaned_data['category']
      else:
          form = SearchForm()
      return render_to_response("books/create.html", {
          "form": form,
      }, context_instance=RequestContext(request))
  </code></pre>
  
  <p>The form shows up fine, but when I submit it I get an error: <code>'SearchForm' object has no attribute 'cleaned_data'</code></p>
  
  <p>I'm not sure what's going on, can someone help me out? Thanks!</p>