Question

我有两个相互关联的模型。

class FAQCategory(models.Model):
    title = models.CharField(max_length=50, null=True, blank=True)       

    def __str__(self):
        return self.title

class FAQ(models.Model):
    category = models.ForeignKey(FAQCategory, on_delete=models.SET_NULL, null=True, blank=True)
    question = models.CharField(max_length=100, null=True, blank=True)
    answer = models.TextField(max_length=10000, null=True, blank=True)

我有一个常见问题查询集。

faq_list = FAQ.objects.filter(user=user).exclude(answer="").exclude(question="").exclude(category=None)

如何获取faq_list中表示的唯一FAQCategory实例的查询集？

faq_category_list = FAQCategory.objects.filter( ...appear in faq_list... )

谢谢！

Answer 1

一种简单的方法是在第一个查询中获取pk数组，然后在下一个查询中使用它

faq_list = FAQ.objects.filter(user=user).exclude(answer="").exclude(question="").exclude(category=None).values_list('pk',flat=True) # list of ids

faq_category_list = FAQCategory.objects.filter(faq__id__in=faq_list)

但是两次查询数据库的结果都不被接受

所以最好使用Q对象并执行一个查询

from django.db.models import Q

faq_category_list = FAQCategory.objects.filter(faq__user=user, (
       ~Q(faq__answer="") & ~Q(faq__question="") & ~Q(faq__category=None)
))

Answer 2

# I think you want to get the unique title in FAQCategory model, but for that you don't need to query the database table again. You can get the data from 'faq_list'.

# if you want to have the unique data for title
faq_category_list = list(set([str(fa.category.title) for fa in faq]))

# If you don't want to have the unique data for title in FAQCategory
faq_category_list = [str(fa.category.title) for fa in faq]

print(faq_category_list)

Answer 3

我知道了

faq_category_list = FAQCategory.objects.filter(faq__in=faq_list)

获取仅出现在另一个查询集中的相关模型的查询集

3 个答案: