title: Using Multiple ModelForms with Class-Based Views
body: <p>I've got a situation where I'd like to add an additional modelform to my CreateView. We have an entry order system
  that allows someone to add an order and then add items to that order. Typically, when someone adds an order for the first
  time they'd like to also add an item to that order, so I want to combine those models into a single form and process them 
  on initial order entry. I'm running into a problem when the forms don't validate. </p>
  
  <p>I've overridden get_context_data to add the item form to the template and I've overridden post to process the extra form. But
  when the forms are invalid I need to re-render the original form passing in the POST data. What's the preferred way to override
  get_context_data in order to render the forms with/without the POST data? Should I do something like this?</p>
  
  <pre><code>def get_context_data(self, **kwargs):
      context = super(OrderAdd, self).get_context_data(**kwargs)
      if self.request.method == 'POST':
          item_form = ItemForm(self.request.POST, prefix='item')
      else:
          item_form = ItemForm(prefix='item')
      context['item_form'] = item_form
      return context
  </code></pre>
  
  <p>Here's my CreateView in it's current form, where I'm currently stuck.</p>
  
  <pre><code>class OrderAdd(CreateView):
      model = Order
      form_class = OrderForm
      context_object_name = 'object'
      template_name = 'form.html'
  
      def get_context_data(self, **kwargs):
          context = super(OrderAdd, self).get_context_data(**kwargs)
          item_form = ItemForm(prefix='item')
          context['item_form'] = item_form
          return context
  
      def post(self, request, *args, **kwargs):
          order_form = OrderForm(request.POST)
          item_form = ItemForm(request.POST, prefix='item')
  
          if order_form.is_valid() and item_form.is_valid():
              return self.form_valid(order_form)
          else:
              context = self.get_context_data()
              return render(self.request, 'form.html', context)
  </code></pre>