django - 计算多多字段中的值

Question

我正在尝试从一组具有多字段的对象中计算不同的值

例如

对象文章有许多标签对象字段

---

一篇文章有​​标签“tag1”“tag2”

另一篇文章有​​标签“tag2”“tag3”

---

我想弄清楚一些会返回以下内容的东西：

“标签 1”：1 “标签 2”：2 “标签 3”：1

我以为我可以用articles.objects.all().values('tags') 或其他东西做点什么，但我空了。

Answer 1

模型.py

class Topping(models.Model):
        name = models.CharField(max_length = 20)

class Pizza(models.Model):
        name = models.CharField(max_length = 20)
        toppings = models.ManyToManyField(Topping)

python manage.py 外壳

>>> from many_to_many.models import Pizza, Topping
>>> t1 = Topping(name = "T1")
>>> t2 = Topping(name = "T2")
>>> t3 = Topping(name = "T3")
>>> t4 = Topping(name = "T4")
>>> p1 = Pizza(name="P1")
>>> p2 = Pizza(name="P2")


>>> p1.toppings.add(t1)
>>> p1.toppings.add(t2)
>>> p2.toppings.add(t2)
>>> p2.toppings.add(t3)


>>> t2.pizza_set.count() 
    2
>>> t1.pizza_set.count() 
    1

Answer 2

你的问题是相关的：How to count and display objects in related ManyToMany in Django

模型.py

class Topping(models.Model):
        name = models.CharField(max_length = 20)

class Pizza(models.Model):
        name = models.CharField(max_length = 20)
        toppings = models.ManyToManyField(Topping)

python manage.py 外壳

>>> for topping in Topping.objects.all():
...     print topping.name, topping.pizza_set.count()