Django过滤具有至少一个多对多且具有value属性的对象 [英] Django filter objects with at least one many-to-many having attribute of value
问题描述
我正在使用Django的ORM进行复杂的过滤.
I'm looking to do a complex filter using Django's ORM.
型号:
class Book(models.Model):
title = models.TextField()
bestseller = models.BooleanField(default=False)
class Author(models.Model):
name = models.TextField()
books = models.ManytoManyField(Book)
我将如何查询至少拥有一本畅销书的所有作者?
How would I query for all authors who have at least one best-selling book?
查询:
best_authors = Author.objects.filter(<relevant filter>)
根据文档,以下内容应该起作用:
According to the documentation, the following should work:
best_authors = Author.objects.filter(books__bestseller=True)
不幸的是,最终结果是返回了重复的作者对象(一遍又一遍,每本畅销书的作者都是同一作者).
Unfortunately, that ends up returning repeated author objects (the same author for each bestselling book of his/hers, over and over).
推荐答案
best_authors = Author.objects.filter(books__bestseller=True).distinct()
filter()
对 Books
表执行 JOIN
,并生成 bestseller == True
的所有行>. distinct()
确保每个作者在结果中仅列出一次.
The filter()
does a JOIN
with the Books
table and produces all rows where bestseller==True
. The distinct()
ensures that each author is listed only once in the results.
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