在同一jango模型中的另一个字段中计算不同值内的不同值

Question

我试图从我的django模型表中提取一些分析。到目前为止，我可以计算字段的总价值和字段的不同值。我还知道如何创建列表，显示不同字段中字段的总价值。现在，我想计算不同的实例--一个字段出现在一个不同字段的不同值列表中。这是我正在工作的桌子：

| uid   |  cid   |
|-------|--------|
| a     | apple  |
| a     | apple  |
| a     | grape  |
| b     | apple  |
| b     | grape  |
| c     | apple  |
| c     | pear   |
| c     | pear   |
| c     | pear   |

所以我想提供的结果是：

cid: apple (distinct uid count: 3),
cid: grape (distinct uid count: 2),
cid: pear (distinct uid count: 1)

还包括：

cid apple's distinct uid's: a, b, c
cid grape's distinct uid's: a, b
cid pear's distinct uid's: c

到目前为止，我已经得到了如下明确的计数和列表：

dist_uid_list = Fruit.objects.filter(client=user).values('uid').distinct()
output >>> {'uid': 'a', 'uid': 'b', 'uid': 'c'}

这是：

dist_uid_count = Fruit.objects.filter(client=user).values('uid').distinct().count()
output >>> {3}

更复杂的是：

total_actions_per_cid = Fruit.objects\
            .filter(client=user)\
            .values('cid').distinct()\
            .annotate(num_actions=Count('action_name'))\
            .order_by('cid')
output >>> {'cid': 'apple', 'num_actions': '4'}{'cid': 'grape', 'num_actions': '2'}{'cid': 'pear', 'num_actions': '3'}

，所以这里有一个问题:我怎么才能进去，把每个不同的‘in’都取出来，然后计算出每个‘uid’存在多少个？？

以下是所有可能有助于查看的django文件：

models.py

class Fruit(models.Model):
    uid = models.CharField(max_length=50, blank=True)
    cid = models.CharField(max_length=50, blank=True)
    record_date = models.DateTimeField(auto_now_add=True)
    client = models.CharField(max_length=50, blank=True)
    action_name = models.CharField(max_length=50, blank=True)

views.py

class DashboardListView(LoginRequiredMixin, ListView):
    model = Fruit
    template_name = 'blog/dashboard.html'
    context_object_name = 'fruit'
    ordering = ['-record_date']
    
    def get_context_data(self, **kwargs):
        user = get_object_or_404(User, username=self.kwargs.get('username'))
        context = super().get_context_data(**kwargs)
        dist_uid_list = Fruit.objects.filter(client=user).values('uid').distinct()
        dist_uid_count = Fruit.objects.filter(client=user).values('uid').distinct().count()
        total_actions_per_cid = Fruit.objects\
            .filter(client=user)\
            .values('cid').distinct()\
            .annotate(num_actions=Count('action_name'))\
            .order_by('cid')
        context['dist_uid_list'] = dist_uid_list
        context['dist_uid_count'] = dist_uid_count
        context['total_actions_per_cid'] = total_actions_per_cid

html输出

{% for user in dist_uid_list %}
    {{ user.uid }}
{% endfor %}

    {{ dist_uid_count }}

{% for action in total_actions_per_cid %}
    {{ num_actions }}
{% endfor %}

我假设需要在视图中包含一些for循环操作和多个防御措施，才能使这一工作正常进行。我只是不知道该怎么做。

Answer 1

计数聚合有一个不同的参数，可能有助于：

>>> q = Book.objects.annotate(Count('authors', distinct=True), Count('store', distinct=True))

https://docs.djangoproject.com/en/3.1/topics/db/aggregation/#combining-multiple-aggregations

因此，您的查询将类似于：

# I removed the distinct after .values, as the values works
# like a GROUP BY, thus you will get already unique 'cid's
total_actions_per_cid = Fruit.objects\
            .filter(client=user)\
            .values('cid') \
            .annotate(num_uids=Count('uid', distinct=True))