Redirect a URL from one class-based view to another

When moving my blog from WordPress to Django I changed the structure of the permalinks, before it was not used categoryin the structure and now it is. More or less so:

/slug/ ⟼ /cat/slug/

And so I'm getting a lot of 404 errors, because Django only searches on category. So I decided to add a finder in the class-based view of the categories:

class CategoryDetail(ListView, CacheMixin):
    model = Entry
    paginate_by = 6

    def get_queryset(self):
        self.cat = get_object_or_404(Category, slug=self.kwargs['slug'])
        return Entry.objects.filter(
            category=self.cat, status=Entry.LIVE_STATUS).select_related() \
            .order_by('-pub_date', 'id')

In the function get_querysetI want to add a redirect that calls the class EntryDetailif the slugcorresponds to an entry and not a category.

I do it like this:

def get_queryset(self):
    try:
        entry = Entry.objects.get(slug=self.kwargs['slug'])
        return redirect(entry)
    except Entry.DoesNotExist:
        pass
    self.cat = get_object_or_404(Category, slug=self.kwargs['slug'])
    return Entry.objects.filter(
        category=self.cat, status=Entry.LIVE_STATUS).select_related() \
        .order_by('-pub_date', 'id')

I use the slugto search for the input (if it doesn't find it , I catch the exception DoesNotExistand go on to find the category) and if that entry exists, I redirect the request to the indicated input, which contains the property get_absolute_url()as indicated in the documentation with return redirect(entry). But it does not work.

It also doesn't work if I use this form of redirect, which matches the URL pattern:

# En urls.py: 
# url(r'^(?P<cat>[-\w]+)/(?P<slug>[-\w]+)/$', EntryDetail.as_view(), name="entry_detail")    
return redirect('entry_detail', cat=entry.category, slug=entry.slug)

The problem, in both cases, is that I get the following error:

TypeError at /el-circulo/
object of type 'HttpResponseRedirect' has no len()

The function len()is used for paging, because I keep sending the response to the CBV CategoryDetail.

How can I get the wording I need to work?

That is, how can I leave the class that was called by the request and return the response with a different class, in this case with EntryDetail.