performance: tune the emission view

Down from 179 to 11 queries.

panikweb/views.py

@@ -24,7 +24,7 @@ class EmissionDetailView(DetailView):
     def get_context_data(self, **kwargs):
         context = super(EmissionDetailView, self).get_context_data(**kwargs)
         context['sectionName'] = "Emissions"
-        context['schedules'] = Schedule.objects.filter(emission=self.object).order_by('datetime')
+        context['schedules'] = Schedule.objects.select_related().filter(emission=self.object).order_by('datetime')
 
         # get all episodes, with an additional attribute to get the date of
         # their first diffusion
@@ -42,7 +42,7 @@ class EmissionDetailView(DetailView):
 
         # get all related soundfiles in a single query
         soundfiles = {}
-        for soundfile in SoundFile.objects.filter(podcastable=True,
+        for soundfile in SoundFile.objects.select_related().filter(podcastable=True,
                 fragment=False, episode__emission=self.object):
             soundfiles[soundfile.episode_id] = soundfile