feat: re-organize context for templates using a mixin

context that will be shared across views of the districts app is
moved into the DistrictContextMixin. This reduces context duplication,
both when different views need the same context and also when the view
may not need the context, but the template it extends does need it.
Note that because of how the MRO and mixins work, DistrictContextMixin
inherits from TemplateView.

Author: lalver1

pems/districts/templates/districts/district.html

@@ -1,7 +1,7 @@
 {% extends "districts/index.html" %}
 
 {% block headline %}
-    District {{ url_district }} - {{ district_query.name }}
+    District {{ district_number }} - {{ district.name }}
 {% endblock headline %}
 
 {% block district-content %}
@@ -15,7 +15,7 @@ <h2>Chart</h2>
     </div>
     <div class="row">
         <div class="col-lg-4 border">
-            <h2>Details for {{ district_query.name }}</h2>
+            <h2>Details for {{ district.name }}</h2>
         </div>
         <div class="col-lg-8 border">
             <h2>Map</h2>

pems/districts/templates/districts/index.html

@@ -11,7 +11,7 @@
                 <!-- Side navigation -->
                 <nav aria-labelledby="navigation-list" class="side-navigation">
                     <ul class="list-navigation">
-                        {% for district in district_queryset %}
+                        {% for district in districts.all %}
                             <li>
                                 <a href="{% url 'districts:district' district.number %}">District {{ district.number }}</a>
                             </li>

pems/districts/views.py

@@ -3,22 +3,26 @@
 from .models import District
 
 
-class IndexView(TemplateView):
-    template_name = "districts/index.html"
+class DistrictContextMixin:
 
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
-        context["district_queryset"] = District.objects.all()
+        districts_ctx = {}
+        districts_ctx["all"] = District.objects.all()
+        context["districts"] = districts_ctx
         return context
 
 
-class DistrictView(TemplateView):
+class IndexView(DistrictContextMixin, TemplateView):
+    template_name = "districts/index.html"
+
+
+class DistrictView(DistrictContextMixin, TemplateView):
     template_name = "districts/district.html"
 
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
-        district = self.kwargs.get("district")
-        context["url_district"] = district
-        context["district_queryset"] = District.objects.all()
-        context["district_query"] = District.objects.all().get(number=district)
+        district_number = self.kwargs.get("district")
+        context["district_number"] = district_number
+        context["district"] = context.get("districts").get("all").get(number=district_number)
         return context

tests/pytest/pems/districts/test_views.py

@@ -4,7 +4,7 @@
 from pems.districts.models import District
 
 
-class TestIndexViewView:
+class TestIndexView:
     @pytest.fixture
     def view(app_request):
         v = views.IndexView()
@@ -17,7 +17,7 @@ def test_get_context_data(self, view):
 
         context = view.get_context_data()
 
-        assert set(context["district_queryset"]) == set(District.objects.all())
+        assert set(context.get("districts").get("all")) == set(District.objects.all())
 
     def test_template_name(self, view):
         assert view.template_name == "districts/index.html"
@@ -37,7 +37,7 @@ def test_get_context_data(self, view):
 
         context = view.get_context_data()
 
-        assert context["url_district"] == 1
+        assert context["district_number"] == 1
 
     def test_template_name(self, view):
         assert view.template_name == "districts/district.html"