Django过滤具有至少一个多对多且具有value属性的对象

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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