gistfile1.py

from django.http import HttpResponse
from piston.resource import Resource

class FileResource(Resource):
    def __init__(self, handler, authentication=None, filename=None):
        if filename:
            self.filename = filename
        else:
            self.filename = "export.txt"
        super(FileResource, self).__init__(handler, authentication=authentication)
        
    def __call__(self, request, *args, **kwargs):
        response = super(FileResource, self).__call__(request, *args, **kwargs)
        if isinstance(response, HttpResponse):
            response['Content-Disposition'] = 'attachment; filename=%s' % self.filename
        return response