Rotation editing

Setting the rotation level of a song is a manager’s job, so it can only be done in the admin interface. When I wrote about the schedule I talked about changing the admin interface to do what I want, and we need a new view to edit songs in rotation. In the rotation admin, I’ve included a function to get the count of songs with a link to the new view, and included it in the list.

    list_display = ('rotation', 'max', 'admin_song_count')
    
    def admin_song_count(self, obj):
        return u"%d" % obj.song_set.all().count()
    admin_song_count.short_description = u"Number of songs"
    admin_song_count.allow_tags = True

Now that we’ve got an URL, we need to link it to a view.

    def get_urls(self):
        urls = super(RotationAdmin, self).get_urls()
        my_urls = patterns('', 
            (r'^songs/$', self.admin_site.admin_view(self.changesongs))
        )
        return my_urls+urls

See that link at the start about the joy of a flexible admin interface. changesongs is almost straight forward.

    def changesongs(self, request):
        if request.POST:
            form = RotationSongFormSet(request.POST, queryset=models.Song.objects.filter(rotation__isnull=False).select_related('rotation', 'artist', 'album').order_by('rotation__max', 'added_on'))
            
            if form.is_valid():
                form.save()
                return HttpResponseRedirect("../")
        else:
            form = RotationSongFormSet(queryset=models.Song.objects.filter(rotation__isnull=False).select_related('rotation', 'artist', 'album').order_by('rotation__max', 'added_on'))
            
        context = {
            "title" : "Move rotation songs",
            "formset" : form,
            "opts" : self.model._meta,
            "app_label" : self.model._meta.app_label,
            "root_path": self.admin_site.root_path,
            "has_change_permission" : True,
        }
        context_instance = template.RequestContext(request, current_app=self.admin_site.name)
        return render_to_response("dj_pro/admin/change_rotation_songs.html", context, context_instance)

The only interesting things are the extra entries in context, which are used by the admin templates, and the extra long queryset. Let’s look at it closely: queryset = models.Song.objects.filter (rotation__isnull=False).select_related ('rotation', 'artist', 'album').order_by ('rotation__max', 'added_on'). We only get songs that have a rotation level, include related info, and order by rotation, and the day it was added. The order will be used by the formset, so all that the template needs is

  {% for f in formset.forms %}
  <tr>
    <td>{{f.instance.song}}</td>
    <td>{{f.instance.artist|default:""}}</td>
    <td>{{f.instance.album}} #{{f.instance.album.location}}</td>
    <td>{{f.instance.added_on|date:"SHORT_DATE_FORMAT"}}
    <td>{{f.id}}{{f.rotation}}
      {% if f.rotation.errors %}{{f.rotation.errors}}{% endif %}
    </td>
    <td>{{f.DELETE}}</td>
  </tr>
  {% endfor %}

The DELETE field is another thing altogether. Next post.