我可以像这样在django模型中使用注释吗？

Question

models.py

matches = models.ManyToManyField('Matches') 
... 
def get_rating(self): 
    from django.db.models import Sum, Value, IntegerField 
    from django.db.models.functions import Coalesce 

    return self.matches.annotate(rating=Coalesce(Sum('matches__rating_difference'), Value(0), output_field=IntegerField()) + Value(1000)) 

rating_difference包含玩家等级分

get_rating应该返回点的总和（玩家等级）

template.html

{{ player.matches.get_rating.(?)rating }} 

Answer 1

它的工作原理

models.py

matches = models.ManyToManyField('Matches') 
... 
def get_rating(self): 
    from django.db.models import Sum, Value, IntegerField 
    from django.db.models.functions import Coalesce 

    return self.matches.aggregate(rating=Coalesce(Sum('rating_difference'), Value(0), output_field=IntegerField()) + Value(1000)) 

template.py

{{ player.matches.get_rating.rating_difference }}