A couple of utility class-based views we use at The Texas Tribune.

generic.py

from django.http import HttpResponse
from django.shortcuts import redirect
from django.views.generic.detail import BaseDetailView, \
    SingleObjectTemplateResponseMixin

from tt.url.unicode import urlencode


class CanonicalUrlBaseDetailView(BaseDetailView):

    # If GET parameters are significant, full_path should be True.
    full_path = False

    def get_object(self):
        '''
        Returns a redirect HttpResponse or the requested object.
        
        If the requested URL doesn't match the result of the object's
        get_absolute_url method, redirect to that URL.
        '''
        obj = super(CanonicalUrlBaseDetailView, self).get_object()
        current_url = self.request.get_full_path() if self.full_path else \
            self.request.path
        canonical_url = obj.get_absolute_url()
        if not current_url.startswith(canonical_url):
            if not self.full_path and self.request.GET:
                # Preserve GET parameters if they don't affect the object.
                canonical_url = '?'.join([canonical_url, urlencode(self.request.GET)])
            return redirect(canonical_url, permanent=True)
        else:
            return obj

    def get(self, request, **kwargs):
        response_or_object = self.get_object()
        if isinstance(response_or_object, HttpResponse):
            return response_or_object
        self.object = response_or_object
        context = self.get_context_data(object=self.object)
        return self.render_to_response(context)


class CanonicalUrlDetailView(SingleObjectTemplateResponseMixin,
        CanonicalUrlBaseDetailView):
    pass

preview.py

from django.utils.cache import add_never_cache_headers
from django.views.generic.detail import SingleObjectTemplateResponseMixin, \
    BaseDetailView


class PreviewBaseDetailView(BaseDetailView):
    preview_queryset = None

    def is_request_preview(self):
        return 'preview' in self.request.GET

    def viewer_can_preview(self):
        return self.request.user.is_staff
        
    def get_default_queryset(self):
        return super(PreviewBaseDetailView, self).get_queryset()

    def get_preview_queryset(self):
        qs = getattr(self, 'preview_queryset', None)
        if qs is None:
            qs = self.get_default_queryset()
        return qs._clone()

    def get_queryset(self):
        if self.is_request_preview() and self.viewer_can_preview():
            return self.get_preview_queryset()
        else:
            return self.get_default_queryset()

    def get(self, request, **kwargs):
        response = super(PreviewBaseDetailView, self).get(request, **kwargs)
        if self.is_request_preview():
            add_never_cache_headers(response)
        return response


class PreviewDetailView(SingleObjectTemplateResponseMixin, PreviewBaseDetailView):
    pass