I am using django multi-table inheritance: Video and Image are models derived from Media. I have implemented two views: video_list and image_list, which are just proxies to media_list. media_list returns images or videos (based on input parameter model) for a certain object, which can be of type Event, Member, or Crag. The view alters its behaviour based on input parameter action (better name would be mode), which can be of value "edit" or "view".

The problem is that I need to ask whether the input parameter model contains Video or Image in media_list so that I can do the right thing. Similar condition is also in helper method media_edit_list that is called from the view.

I don't particularly like it but the only alternative I can think of is to have separate (but almost the same) logic for video_list and image_list and then probably also separate helper methods for videos and images: video_edit_list, image_edit_list, video_view_list, image_view_list. So four functions instead of just two. That I like even less because the video functions would be very similar to the respective image functions. What do you recommend?

Here is extract of relevant parts: http://pastebin.com/07t4bdza. I'll also paste the code here:

#urls
url(r'^media/images/(?P<rel_model_tag>(event|member|crag))/(?P<rel_object_id>\d+)/(?P<action>(view|edit))/$', views.image_list, name='image-list')
url(r'^media/videos/(?P<rel_model_tag>(event|member|crag))/(?P<rel_object_id>\d+)/(?P<action>(view|edit))/$', views.video_list, name='video-list')



#views
def image_list(request, rel_model_tag, rel_object_id, mode):
    return media_list(request, Image, rel_model_tag, rel_object_id, mode)


def video_list(request, rel_model_tag, rel_object_id, mode):
    return media_list(request, Video, rel_model_tag, rel_object_id, mode)


def media_list(request, model, rel_model_tag, rel_object_id, mode):
    rel_model = tag_to_model(rel_model_tag)
    rel_object = get_object_or_404(rel_model, pk=rel_object_id)

    if model == Image:
        star_media = rel_object.star_image
    else:
        star_media = rel_object.star_video

    filter_params = {}
    if rel_model == Event:
        filter_params['event'] = rel_object_id
    elif rel_model == Member:
        filter_params['members'] = rel_object_id
    elif rel_model == Crag:
        filter_params['crag'] = rel_object_id

    media_list = model.objects.filter(~Q(id=star_media.id)).filter(**filter_params).order_by('date_added').all()

    context = {
        'media_list': media_list,
        'star_media': star_media,
    }

    if mode == 'edit':
        return media_edit_list(request, model, rel_model_tag, rel_object_id, context)

    return media_view_list(request, model, rel_model_tag, rel_object_id, context)


def media_view_list(request, model, rel_model_tag, rel_object_id, context):
    if request.is_ajax():
        context['base_template'] = 'boxes/base-lite.html'
    return render(request, 'media/list-items.html', context)


def media_edit_list(request, model, rel_model_tag, rel_object_id, context):
    if model == Image:
        get_media_edit_record = get_image_edit_record
    else:
        get_media_edit_record = get_video_edit_record

    media_list = [get_media_edit_record(media, rel_model_tag, rel_object_id) for media in context['media_list']]

    if context['star_media']:
        star_media = get_media_edit_record(context['star_media'], rel_model_tag, rel_object_id)
    else:
        star_media = None

    json = simplejson.dumps({
        'star_media': star_media,
        'media_list': media_list,
    })
    return HttpResponse(json, content_type=json_response_mimetype(request))


def get_image_edit_record(image, rel_model_tag, rel_object_id):
    record = {
        'url': image.image.url,
        'name': image.title or image.filename,
        'type': mimetypes.guess_type(image.image.path)[0] or 'image/png',
        'thumbnailUrl': image.thumbnail_2.url,
        'size': image.image.size,
        'id': image.id,
        'media_id': image.media_ptr.id,
        'starUrl':reverse('image-star', kwargs={'image_id': image.id, 'rel_model_tag': rel_model_tag, 'rel_object_id': rel_object_id}),
    }
    return record


def get_video_edit_record(video, rel_model_tag, rel_object_id):
    record = {
        'url': video.embed_url,
        'name': video.title or video.url,
        'type': None,
        'thumbnailUrl': video.thumbnail_2.url,
        'size': None,
        'id': video.id,
        'media_id': video.media_ptr.id,
        'starUrl': reverse('video-star', kwargs={'video_id': video.id, 'rel_model_tag': rel_model_tag, 'rel_object_id': rel_object_id}),
    }
    return record




# models
class Media(models.Model, WebModel):
    title = models.CharField('title', max_length=128, default='', db_index=True, blank=True)
    event = models.ForeignKey(Event, null=True, default=None, blank=True)
    crag = models.ForeignKey(Crag, null=True, default=None, blank=True)
    members = models.ManyToManyField(Member, blank=True)
    added_by = models.ForeignKey(Member, related_name='added_images')
    date_added = models.DateTimeField('date added', auto_now_add=True, null=True, default=None, editable=False)


class Image(Media):
    image = ProcessedImageField(upload_to='uploads',
                                processors=[ResizeToFit(width=1024, height=1024, upscale=False)],
                                format='JPEG',
                                options={'quality': 75})
    thumbnail_1 = ImageSpecField(source='image',
                                processors=[SmartResize(width=178, height=134)],
                                format='JPEG',
                                options={'quality': 75})
    thumbnail_2 = ImageSpecField(source='image',
                                #processors=[SmartResize(width=256, height=192)],
                                processors=[ResizeToFit(height=164)],
                                format='JPEG',
                                options={'quality': 75})


class Video(Media):
    url = models.URLField('url', max_length=256, default='')
    embed_url = models.URLField('embed url', max_length=256, default='', blank=True)
    author = models.CharField('author', max_length=64, default='', blank=True)
    thumbnail = ProcessedImageField(upload_to='uploads',
                                processors=[ResizeToFit(width=1024, height=1024, upscale=False)],
                                format='JPEG',
                                options={'quality': 75}, null=True, default=None, blank=True)
    thumbnail_1 = ImageSpecField(source='thumbnail',
                                processors=[SmartResize(width=178, height=134)],
                                format='JPEG',
                                options={'quality': 75})
    thumbnail_2 = ImageSpecField(source='thumbnail',
                                #processors=[SmartResize(width=256, height=192)],
                                processors=[ResizeToFit(height=164)],
                                format='JPEG',
                                options={'quality': 75})

  class Crag(models.Model, WebModel):
      name = models.CharField('name', max_length=64, default='', db_index=True)
      normalized_name = models.CharField('normalized name', max_length=64, default='', editable=False)
      type = models.IntegerField('crag type', null=True, default=None, choices=crag_types)
      description = models.TextField('description', default='', blank=True)
      country = models.ForeignKey('country', null=True, default=None) #TODO: make this not null when db enables it
      latitude = models.FloatField('latitude', null=True, default=None)
      longitude = models.FloatField('longitude', null=True, default=None)
      location_index = FixedCharField('location index', length=24, default='', editable=False, db_index=True) # handled by db, used for marker clustering
      added_by = models.ForeignKey('member', null=True, default=None)
      #route_count = models.IntegerField('route count', null=True, default=None, editable=False)
      date_created = models.DateTimeField('date created', auto_now_add=True, null=True, default=None, editable=False)
      last_modified = models.DateTimeField('last modified', auto_now=True, null=True, default=None, editable=False)
      star_image = models.ForeignKey('Image', null=True, default=None, related_name='star_crags', on_delete=models.SET_NULL)
      star_video = models.ForeignKey('Video', null=True, default=None, related_name='star_crags', on_delete=models.SET_NULL)