pass a query param to a form

views.py

from .forms import AccountCreationForm


class IndexView(TemplateView):
    template_name = 'myapp/mytemplate.html'

    def get_context_data(self, **kwargs):
        ctx = super(IndexView, self).get_context_data(**kwargs)
        # you can use any query param key you'd like...
        ctx['form'] = AccountCreationForm(initial={'promotion_code': self.request.GET.get('c', '')})
        return ctx