问在M2M中通过存在来标注查询

EN

from django.db import models

class ModelA(models.Model):
    title = models.CharField(max_length=100)


class ModelB(models.Model):
    title = models.CharField(max_length=100)
    a_objects = models.ManyToManyField(ModelA, related_name='b_objects')

from django.db.models import Case, When, Value

b_object = ModelB.objects.get(id=some_id)

QS0 = ModelA.objects.annotate(is_linked_to_b=Case(When(b_objects__id=b_object, then=Value(True)), default=Value(False), output_field=BooleanField())

# QSO[some_index].is_linked_to_b should return either True or False.