Django Generic Views: When to use ListView vs. DetailView

Question

I am using Django's class based generic views in a blog application. One of my views displays a list of posts that have a certain tag. I can write this view as a ListView of posts, filtered by tag. Or I can write this view as a DetailView of the tag, and add the relevant posts to the context.

Is one way more proper -- or Pythonic -- than the other?

The ListView approach seems more semantic, because what I want is a list of posts, but it's also slightly more complex. It requires that I overwrite two methods. The DetailView approach only requires me to overwrite one method.

class PostTagView(ListView):
    """Display all blog posts with a given tag."""
    queryset = Post.objects.published()

    def get_context_data(self, **kwargs):
        context = super(PostTagView, self).get_context_data(**kwargs)
        context['tag'] = get_object_or_404(Tag, slug=self.kwargs['slug'])
        return context

    def get_queryset(self, **kwargs):
        queryset = super(PostTagView, self).get_queryset()
        return queryset.filter(tags__slug=self.kwargs['slug'])


class TagDetailView(DetailView):
    """Display all blog posts with a given tag."""
    model = Tag

    def get_context_data(self, **kwargs):
        context = super(TagDetailView, self).get_context_data(**kwargs)
        context['object_list'] = Post.objects.published().filter(tags__slug=self.kwargs['slug'])
        return context

Solution 1

As a rule of thumb, look at the parameters in the URL. If you're using a slug of a Tag then you're most likely dealing with a DetailView and not a ListView.

In this case, the second approach uses less code and it is more elegant. However, it also depends on what you're going to do with the view later on. If you're going to add forms to edit the posts, it might make sense to use a ListView instead. But there's no technical reason to prefer one over the other, it's just that you might end up writing more code in one approach than in the other.

Solution 2

Both ListView and DetailView are not the same technically, For example you cannot give the path for a DetailView like the below in urls.py,

path('schools_detail/',views.SchoolDetailView.as_view(),name = "detail"),

This will give the below error,

Generic detail view SchoolDetailView must be called with either an object pk or a slug in the URLconf.

This means that if we have a table called Student and another table called School, we can use the ListView to list all the schools like below,

path('list/',views.SchoolListView.as_view(),name = "list"),

And if we want to list the Schools details for individual school when we click the school icon, then we can use the primary key of the School which Django creates internally and capture it in the url pattern, in my case the url pattern would be "list/{{school.id}}" so to capture this we have to give the path like below for DetailsView,

path('list/<int:pk>/',views.SchoolDetailView.as_view(),name = "detail"),

So Bottom line is you can use the ListView as a normal view for most of the cases, if you want to access another View but only a particular detail in that View which refers with a primary key then you can use DetailsView(the url pattern for the DetailsView will be generated by giving the primary key info in the url, without primary key in the url it wont work since it wont take all the info instead it will only take the info related to the primary key in the url)

Solution 3

Interesting question. Unfortunately, the answer is not quite so interesting: whichever makes the most sense for you and your app. Arguments could be made equally for either approach, so it's really just a judgement call.