Add last-modified to article view

src/articles/tests/test_html_views.py

@@ -52,6 +52,7 @@ def _assert_article_is_rendered(item: Article, res: HttpResponse) -> None:
     assert item.title in content
     html = item.get_formatted_content
     assert html in content
+    assert "Last-Modified" in res.headers
 
 
 @pytest.mark.django_db()

src/articles/views/html/single_article.py

@@ -1,10 +1,24 @@
+import datetime
+
 from django.core.handlers.wsgi import WSGIRequest
 from django.http import HttpResponse
 from django.shortcuts import get_object_or_404, render
+from django.views.decorators.http import last_modified
 
 from articles.models import Article
 
 
+def get_article_last_modified(request: WSGIRequest, slug: str) -> datetime.datetime:
+    key = request.GET.get("draft_key")
+    qs = Article.objects.all().only("updated_at")
+    if key:
+        return get_object_or_404(qs, draft_key=key, slug=slug).updated_at
+    if not request.user.is_authenticated:
+        qs = qs.filter(status=Article.PUBLISHED)
+    return get_object_or_404(qs, slug=slug).updated_at
+
+
+@last_modified(get_article_last_modified)
 def view_article(request: WSGIRequest, slug: str) -> HttpResponse:
     article = get_article(request, slug)
     if not request.user.is_authenticated: