Cache the bug detail page

We can do this with no timeout because we have the bug's modified_at
timestamp, which changes whenever any action is done on the bug.

If we ever implement editing of titles, this will be problematic,
because bug mentions include the other bug's title. If the other bug's
title gets updated, the cached rendered markdown won't be updated.

buggy/models.py

@@ -69,6 +69,13 @@ def number(self):
     def get_absolute_url(self):
         return urls.reverse('buggy:bug_detail', kwargs={'bug_number': self.number})
 
+    @property
+    def actions_preloaded(self):
+        return self.actions.select_related(
+            'user', 'comment', 'setpriority', 'setassignment__assigned_to',
+            'setstate', 'setproject', 'settitle',
+        ).prefetch_related('attachments')
+
 
 class Action(models.Model):
     user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.PROTECT)

buggy/templates/buggy/bug_detail.html

@@ -1,10 +1,12 @@
 {% extends "buggy/base.html" %}
 
-{% load buggy_tags thumbnail argonauts absoluteuri %}
+{% load buggy_tags thumbnail argonauts absoluteuri cache %}
 
 {% block title %}{{ block.super }} - {{ bug.title }}{% endblock %}
 
 {% block content %}
+{% cache 31536000 bug_detail bug.id bug.modified_at %}
+
 <script>
   window._harvestPlatformConfig = {
     "applicationName": "Buggy",
@@ -13,6 +15,7 @@
 </script>
 <script async src="https://platform.harvestapp.com/assets/platform.js"></script>
 
+
 <div class="harvest-timer"
   data-item='{"id": {{ bug.number|json|force_escape }}, "name": {{ bug.title|json|force_escape }}}'
   data-group='{"id": {{ bug.project.id|json|force_escape }}, "name": {{ bug.project.name|json|force_escape }}}'
@@ -25,7 +28,7 @@ <h1><input readonly value="#{{ bug.number }}"><a href="{{ bug.project.get_absolu
   state is {{ bug.state }}{% if bug.assigned_to %}, currently assigned to {{ bug.assigned_to.get_short_name }}{% endif %}.
 </p>
 
-{% for action in bug.actions.all %}
+{% for action in bug.actions_preloaded %}
   <section>
     <h1>{{ action.created_at|absolutedate }} {{ action.description }}</h1>
     {% if action.comment %}
@@ -52,6 +55,8 @@ <h3>Attachments</h3>
   </section>
 {% endfor %}
 
+{% endcache %}
+
 {% include "buggy/_bug_form.html" %}
 
 {% endblock %}

buggy/views.py

@@ -145,12 +145,7 @@ def get_form_kwargs(self):
 class BugDetailView(LoginRequiredMixin, BugMutationMixin, FormView):
     template_name = 'buggy/bug_detail.html'
 
-    queryset = Bug.objects.all().prefetch_related(
-        Prefetch('actions', queryset=Action.objects.select_related(
-            'user', 'comment', 'setpriority', 'setassignment__assigned_to',
-            'setstate', 'setproject', 'settitle',
-        ).prefetch_related('attachments'))
-    ).select_related(
+    queryset = Bug.objects.select_related(
         'created_by', 'assigned_to', 'project'
     )