如何使用Django + Haystack +多站点？

from haystack.indexes import SearchIndex, IntegerField

class SiteSearchIndex(SearchIndex):
    site_id = IntegerField(model_attr=\"site__id\")

from django.conf import settings
from django.conf.urls.defaults import patterns, url
from haystack.forms import SearchForm
from haystack.query import SearchQuerySet
from haystack.views import search_view_factory
from myapp.apps.search.views import SearchView

sqs = SearchQuerySet().filter(site_id=settings.SITE_ID).order_by(\"-pub_date\")
urlpatterns = patterns(\"\",
    url(r\"^$\",
        search_view_factory(
            view_class=SearchView, searchqueryset=sqs, form_class=SearchForm
        ),
        name=\"search-index\"
    ),
)