Fix empty-category nav and route behavior

Use category-state-driven queries for nav and category listing routes, and add regression tests for empty but valid categories.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

apps/blog/models.py

@@ -49,10 +49,7 @@ class HomePage(Page):
                 id__in=ArticlePage.objects.live().public().values_list("tags__id", flat=True)
             ).distinct().order_by("name")
         )
-        category_ids = ArticlePage.objects.live().public().values_list("category_id", flat=True)
-        ctx["available_categories"] = Category.objects.filter(show_in_nav=True, id__in=category_ids).order_by(
-            "sort_order", "name"
-        )
+        ctx["available_categories"] = Category.objects.filter(show_in_nav=True).order_by("sort_order", "name")
         return ctx
 
 
@@ -76,9 +73,7 @@ class ArticleIndexPage(RoutablePageMixin, Page):
     def get_listing_context(self, request, active_category=None):
         tag_slug = request.GET.get("tag")
         articles = self.get_articles()
-        all_articles = articles
-        category_ids = all_articles.values_list("category_id", flat=True)
-        available_categories = Category.objects.filter(id__in=category_ids).order_by("sort_order", "name")
+        available_categories = Category.objects.order_by("sort_order", "name")
         category_links = [
             {"category": category, "url": self.get_category_url(category)}
             for category in available_categories
@@ -111,9 +106,7 @@ class ArticleIndexPage(RoutablePageMixin, Page):
 
     @route(r"^category/(?P<category_slug>[-\w]+)/$")
     def category_listing(self, request, category_slug):
-        category_ids = self.get_articles().values_list("category_id", flat=True)
-        category_qs = Category.objects.filter(id__in=category_ids)
-        category = get_object_or_404(category_qs, slug=category_slug)
+        category = get_object_or_404(Category, slug=category_slug)
         return self.render(request, context_overrides=self.get_listing_context(request, active_category=category))
 
     def get_context(self, request, *args, **kwargs):

apps/blog/tests/test_views.py

@@ -233,3 +233,14 @@ def test_article_index_category_route_supports_tag_filter(client, home_page):
     assert resp.status_code == 200
     assert "Keep Me" in html
     assert "Drop Me" not in html
+
+
+@pytest.mark.django_db
+def test_article_index_category_route_allows_empty_existing_category(client, home_page):
+    index = ArticleIndexPage(title="Articles", slug="articles")
+    home_page.add_child(instance=index)
+    Category.objects.create(name="Opinion", slug="opinion")
+
+    resp = client.get("/articles/category/opinion/")
+    assert resp.status_code == 200
+    assert "No articles found." in resp.content.decode()

apps/core/templatetags/core_tags.py

@@ -4,7 +4,7 @@ from django import template
 from django.utils.safestring import mark_safe
 from wagtail.models import Site
 
-from apps.blog.models import ArticleIndexPage, TagMetadata
+from apps.blog.models import ArticleIndexPage, Category, TagMetadata
 from apps.core.models import SiteSettings
 from apps.legal.models import LegalPage
 
@@ -58,9 +58,7 @@ def get_categories_nav(context):
     index_page = index_qs.first()
     if not index_page:
         return []
-    categories = index_page.get_listing_context(
-        request, active_category=None
-    )["available_categories"].filter(show_in_nav=True)
+    categories = Category.objects.filter(show_in_nav=True).order_by("sort_order", "name")
     return [
         {
             "name": category.name,

apps/core/tests/test_tags.py

@@ -37,3 +37,14 @@ def test_categories_nav_tag_renders_category_link(client, home_page):
     resp = client.get("/")
     assert resp.status_code == 200
     assert "/articles/category/reviews/" in resp.content.decode()
+
+
+@pytest.mark.django_db
+def test_categories_nav_tag_includes_empty_nav_category(client, home_page):
+    index = ArticleIndexPage(title="Articles", slug="articles")
+    home_page.add_child(instance=index)
+    Category.objects.create(name="Benchmarks", slug="benchmarks", show_in_nav=True)
+
+    resp = client.get("/")
+    assert resp.status_code == 200
+    assert "/articles/category/benchmarks/" in resp.content.decode()