How to set an HTTP header for a JSON message from within a django-piston handler?

In a piston handler, I need to return a django.db.models.query.QuerySet as a proper JSON message (reflective of the underly model and query), while also adding an HttpResponse header of my own. So far, I can do one or the other, but not both (and get a proper looking JSON response).

The below generates a proper JSON formatted response, but with no added HttpResponse header (not shown):

class PollHandlerSearch(BaseHandler):
    allowed_methods = ('POST')
    model = Poll
    fields = ('id', 'question', 'pub_date')
    KEYS =  ( 'question', 'start-date', 'end-date' )

    def create(self, request):
        post = Poll.objects.all()
        for skey in self.KEYS:
            if len(post) and request.POST.has_key(skey) and len(request.POST[skey]):
                if skey == self.KEYS[0]:
                        post = post.filter(question__icontains=request.POST[skey])
                elif skey == self.KEYS[1]:
                        post = post.filter(pub_date__gte=request.POST[skey])
                elif skey == self.KEYS[2]:
                        post = post.filter(pub_date__lte=request.POST[skey])
        return post

Resulting correctly formatted JSON message:

[
    {
        "pub_date": "2010-08-23 22:15:07", 
        "question": "What's up?", 
        "id": 1
    }
]

The below implements an HttpResponse with the added header and generates a JSONish looking response, but one that is not what is being expected or wanted, plus not reflecting whatever django's 'DateTimeAwareJSONEncoder' does (used by piston's JSONEmitter).

class PollHandlerSearch(BaseHandler):
    allowed_methods = ('POST')
    model = Poll
    fields = ('id', 'question', 'pub_date')
    KEYS =  ( 'question', 'start-date', 'end-date' )

    def create(self, request):
        resp = HttpResponse()
        post = Poll.objects.all()
        for skey in self.KEYS:
            if len(post) and request.POST.has_key(skey) and len(request.POST[skey]):
                if skey == self.KEYS[0]:
                        post = post.filter(question__icontains=request.POST[skey])
                elif skey == self.KEYS[1]:
                        post = post.filter(pub_date__gte=request.POST[skey])
                elif skey == self.KEYS[2]:
                        post = post.filter(pub_date__lte=request.POST[skey])
        json_serializer = serializers.get_serializer("json")()
        json_serializer.serialize(post, ensure_ascii=False, indent=4, stream=resp)
        resp['MYHEADER'] = 'abc123'
        return resp

Resulting incorrectly formatted JSONish message:

[
    {
        "pk": 1, 
        "model": "polls.poll", 
        "fields": {
            "pub_date": "2010-08-23 22:15:07", 
            "question": "What's up?"
        }
    }
]

This is no doubt happening since I am doing my own JSON serialization, bypassing piston's JSONEmitter and thus whatever it does to properly render 'post'.

I have been pouring over piston's emitters.py, and largely can't follow it (I am pretty new at OOP / Python / django / piston). How can I get piston to deliver a properly formatted JSON message开发者_如何学编程 with an HTTP header supplemented with headers I provide?

You could subclass piston.resource.Resource, and add whatever header you want in the __call__ method. from piston.resource import Resource

class MyResource(Resource):
    def __call__(self, request, *args, **kwargs):
        resp = super(MyResource, self).__call__(request, *args, **kwargs)
        resp['HEADER'] = "abc123"
        return resp

Then, in your urls.py:

def BasicResource(handler):
    return resource.MyResource(handler=handler, authentication=basic)

your_handler = BasicResource(YourHandlerClass)
another_handler = BasicResource(AnotherHandlerClass)