File handling in Django's FormView - request.FILES is empty

Question

I am trying to implement a FormView in Django, as it seems to cut down on a bit of boilerplate code. One of the fields is a file upload field.

class LibraryUploadLastStageForm(forms.Form):

    technician = forms.ModelChoiceField(label="prepeared by" , queryset=Technician.objects.exclude(has_left=True).order_by('name') , required=True)
    subprojects = forms.ModelChoiceField(label="Choose a subproject" , queryset=Subproject.objects.all().order_by('subproject_name') , required=True)
    lab_tracking_excel = forms.FileField(label="Choose the Lab Tracking Excel - protocol details associated with these libraries", required=False)

in views.py ,

class LibraryUploadFinalView(FormView):

    template_name = 'sequencing/ChooseSomething.html' 
    form_class = LibraryUploadLastStageForm


    def form_valid(self, form):
        """
        Update the library technician, and create the librarysubproject links
        """

        id_list_str = self.request.GET.get('ids')
        ids = map(int , id_list_str.split(','))

        libraries = Library.objects.filter(id__in=ids)
        print libraries.count()

        cd = form.cleaned_data
        lib_kwargs = {}
        for library in libraries : 
            library.technician = cd['technician']
            if cd['lab_tracking_excel']:
                print cd['lab_tracking_excel']
            library.lab_tracking_excel = self.request.FILES
            library.save()    
            LibrarySubprojectStats(subproject=cd['subprojects'],
                               library=library
                               ).save()


        print "updated %s" % library.name

        return super(LibraryUploadFinalView, self).form_valid(form)

The problem is when I am in the FromView form_valid() method (where I am saving the details), seld.request.FILES is empty when I check it in the debugger.

update: I can see the file is stored under form.data, but how do I get it from there to form.cleaned_data - which is empty?