django FilteredRelation 的用法

有两大用处

• FilteredRelation类允许为查询集增加一个ON从句
• 可以在多个join中语句直接引用变量

from django.db.models import FilteredRelation, Q

result_1 = Restaurant.objects.annotate(pizzas_vegetarian=FilteredRelation('pizzas', condition=Q(pizzas__vegetarian=True), ), ).filter(
    pizzas_vegetarian__name__icontains='mozzarella')