做我的第一个真正的Django项目,并且需要指导。在Django中注释导致'None'值的SUM聚合函数
背景: 我的项目是一个reddit克隆。用户提交链接+文字。访问者upvote或downvote。有一个社交排名算法,每运行约2分钟作为背景脚本,根据网络投票和内容新鲜度重新排列所有提交内容。相当香草的东西。
问题: 排序方式votes
无法正常工作,因为votes
被初始化为None
,而不是0
。这会导致None
投票的投稿数量低于提交的反对投票数。我已经调整了这个问题几天 - 没有运气。
具体细节: 我过我缠身模型的模型管理器来标注Sum
聚合函数查询集,然后责令该查询通过“社会地位”和投票设置。下面是我的models.py。我使用Django 1.5
,这样一些东西,你看到这里可能不符合1.8(如get_query_set
VS get_queryset
):
class LinkVoteCountManager(models.Manager):
def get_query_set(self):
return super(LinkVoteCountManager, self).get_query_set().annotate(votes=Sum('vote__value')).order_by('-rank_score', '-votes')
class Link(models.Model):
description = models.TextField(_("Write something"))
submitter = models.ForeignKey(User)
submitted_on = models.DateTimeField(auto_now_add=True)
rank_score = models.FloatField(default=0.0)
url = models.URLField(_("Link"), max_length=250, blank=True)
with_votes = LinkVoteCountManager()
objects = models.Manager()
def __unicode__(self):
return self.description
def set_rank(self):
# Based on reddit ranking algo at http://amix.dk/blog/post/19588
epoch = datetime(1970, 1, 1).replace(tzinfo=None)
netvotes = self.votes # 'NONE' votes are messing up netvotes amount.
if netvotes == None:
netvotes = 0
order = log(max(abs(netvotes), 1), 10)
sign = 1 if netvotes > 0 else -1 if netvotes < 0 else 0
unaware_submission = self.submitted_on.replace(tzinfo=None)
td = unaware_submission - epoch
epoch_submission = td.days * 86400 + td.seconds + (float(td.microseconds)/1000000)
secs = epoch_submission - 1432201843
self.rank_score = round(sign * order + secs/45000, 8)
self.save()
class Vote(models.Model):
voter = models.ForeignKey(User)
link = models.ForeignKey(Link)
value = models.IntegerField(null=True, blank=True, default=0)
def __unicode__(self):
return "%s gave %s to %s" % (self.voter.username, self.value, self.link.description)
如果需要的话,以下是从我的views.py相关章节:
class LinkListView(ListView):
model = Link
queryset = Link.with_votes.all()
paginate_by = 10
def get_context_data(self, **kwargs):
context = super(LinkListView, self).get_context_data(**kwargs)
if self.request.user.is_authenticated():
voted = Vote.objects.filter(voter=self.request.user)
links_in_page = [link.id for link in context["object_list"]]
voted = voted.filter(link_id__in=links_in_page)
voted = voted.values_list('link_id', flat=True)
context["voted"] = voted
return context
class LinkCreateView(CreateView):
model = Link
form_class = LinkForm
def form_valid(self, form):
f = form.save(commit=False)
f.rank_score=0
f.with_votes = 0
f.category = '1'
f.save()
return super(CreateView, self).form_valid(form)
任何人都可以阐明我需要做什么来解决“None
”问题?提前致谢。
如果你设置null = False保持默认= 0? –