Django按多对多对象排序 [英] django order by count of many to many object
问题描述
我有一个模型:
class Category(models.Model):
个问题= models.ManyToManyField( '问题',related_name = cat_question,空白=真)
cat_name = models.CharField(max_length = 50)
cat_description = models.CharField(max_length = 255)
def __unicode __(self):
return self.cat_name
在我看来,我有:
top_categories = Category.objects.all()[:7]。
我在模板中将其作为上下文传递。
我想按问题的数量对排名靠前的类别进行排序,例如,如果A类别的问题最多,那么它应该排在最前;如果B的问题最多,那么B。然后第二位,依此类推。 p>
like top_categories = Category.objects.all()。order_by(Count(question)
有帮助吗?
注释类别
带有问题数量的对象,然后按降序排列:
from django.db.models import Count
top_categories = Category.objects.annotate(q_count = Count('questions'))\
.order_by('-q_count')[:7]
I have a model :
class Category(models.Model):
questions = models.ManyToManyField('Question', related_name="cat_question", blank=True)
cat_name = models.CharField(max_length=50)
cat_description = models.CharField(max_length=255)
def __unicode__(self):
return self.cat_name
and in my view I have :
top_categories = Category.objects.all()[:7].
I am passing it as context in the template. I want to sort the top categories by the number of questions in it like if A category has most question then it should be in top and if B has most question then B. Then second most and so on..
like top_categories = Category.objects.all().order_by(Count(question)
Any help ?
Annotate Category
objects with the number of questions and then order by this number in descend order:
from django.db.models import Count
top_categories = Category.objects.annotate(q_count=Count('questions')) \
.order_by('-q_count')[:7]
and you can look on the example in the doc order-by, more examples for aggreagate cheat-sheet
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