django 查询

› Django Project

› Django REST Framework

This topic created in 2538 days ago, the information mentioned may be changed or developed.

模型

class Author(models.Model):
    """ 作者"""
    name = models.CharField('名字', max_length=64)


class Shop(models.Model):
    """ 书店对某个作者的销售情况"""
    author = models.ForeignKey(Author,on_delete=)
    sales_count =  models.CharField('销售情况', max_length=512, default='')

如和查询 Author，并且能统计该作者在所有书点点销售总数？

5 replies • 2019-06-11 11:42:27 +08:00

tristankuo

Jun 11, 2019

sales_count 不应该是 int 吗？

from django.db.models import Sum
Author.objects.prefetch_related('shops').values('name').annotate(sum_sales_count=Sum('shops__sales_count'))

kingofvir

Jun 11, 2019

在 Author 每指明 MTM 字段能使用 prefetch related('shops')

kingofvir

Jun 11, 2019

@kingofvir 在 Author 没指明 MTM 字段能使用 prefetch related('shops')

kingofvir

Jun 11, 2019

我用了这个
```
Shop.objects.values('author__pk').annotate(
all_sales_count=Sum('sales_count', distinct=True),
name=F('author__name')
)
```

tristankuo

Jun 11, 2019

指定 related_name?
或者用 Shop 查
Shop.objects.select_related('author').values('author__name').annotate(c=Sum('sales_count'))