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[英]Django ORM query to retrieve objects from a table and most recent objects from another foreign-key-related table?
[英]django orm sort by foreign key occurence in another table
假設有類似下表的內容:
class Book(models.Model):
title = models.CharField(max_length=200)
class Purchase(models.Model):
book = models.CharField(Book, db_column="book", on_delete=models.CASCADE)
date = models.DateField()
並希望檢索按購買次數排序的書籍查詢集(即在另一個表中出現外鍵)。
Book.objects.all().annotate(number_of_purchases=Count(**something**)).order_by('number_of_purchases')
這可能嗎? 我目前不知道應該用什么替換“東西”。
您可以使用.annotate(…)
[Django-doc] :
from django.db.models import Count
Book.objects.annotate(
npurchase=Count('purchase')
).order_by('-npurchase')
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