upload.py

# index.html

<form class="" enctype="multipart/form-data" action="{{ upload_url }}" method="post">
  <input type="file" name="file" id="file"><input>
  <input type="submit" name="submit" value="Upload">
</form>

# urls.py -----------------------------------

from django.conf.urls import url

from .views import UploadFormView, UploadFileView

urlpatterns = (
    url(r'^$', UploadFormView.as_view(), name='upload_url'),

    url(r'^upload/$', UploadFileView.as_view(), name='upload'),
)

# view.py -----------------------------------

import json
from django.views.generic import View, TemplateView
from django.http import HttpResponse
from django.core.urlresolvers import reverse
from google.appengine.ext import blobstore


class UploadFormView(TemplateView):
    template_name = 'index.html'

    def get_context_data(self, *args, **kwargs):
        ctx = super(UploadFormView, self).get_context_data(*args, **kwargs)
        ctx['upload_url'] = blobstore.create_upload_url(reverse('upload'))
        return ctx


class UploadFileView(View):
    def post(self, request):
        image = request.FILES.get('file')
        data = image.blobstore_info.open()
        # ... whatever you need to do with PDF
        return HttpResponse(data.read(), content_type="image/png")