如何计数和显示与Django中的ManyToMany关系的对象 [英] How to count and display objects in relation ManyToMany in Django

问题描述

我有一个简单的新闻和类别模型：

I have a simple model with news and categories:

class Category(models.Model):
    name = models.CharField()
    slug = models.SlugField()

class News(models.Model):
    category = models.ManyToManyField(Category)
    title = models.CharField()
    slug = models.SlugField()
    text = models.TextField()
    date = models.DateTimeField()

我想计算每个类别的新闻并将其显示在网站上，如下所示：

I want to count news for each category and display it on the website, like this:

Sport (5)
School (4)
Films (6)
Computer (2)
etc...

我该怎么做？

谢谢！ / p>

Thanks!

推荐答案

从Django 1.1中查看annotate（）函数。

Check out annotate() function from Django 1.1.

a href =http://docs.djangoproject.com/en/dev/topics/db/aggregation/#topics-db-aggregation =noreferrer> http://docs.djangoproject.com/en/dev /主题/ DB /汇聚/＃主题-D b-aggregation

http://docs.djangoproject.com/en/dev/topics/db/aggregation/#topics-db-aggregation

示例（从上面的URL）：

Example (from that URL above):

>>> q = Book.objects.annotate(num_authors=Count('authors'))
>>> q[0].num_authors
2
>>> q[1].num_authors
1

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