django - 如何仅删除 m2m 关系？

Question

模型:

class Province(models.Model):
    user = models.ManyToManyField(User, blank=True)
    name = models.CharField(max_length=30, unique=True)

class City(models.Model):
    name = models.CharField(max_length=100, unique=True)
    slug = models.SlugField(max_length=100, editable=False, unique=False)
    ownership = models.ManyToManyField(User, through='UserCity')


class UserCity(models.Model):
    user = models.ForeignKey(User)
    province = models.ForeignKey(Province)
    city = models.ForeignKey(City)


class District(models.Model):
    name = models.CharField(max_length=100, unique=True)
    slug = models.SlugField(max_length=100, unique=True, editable=False)
    ownership = models.ManyToManyField(User, through='UserDistrict')

class UserDistrict(models.Model):
    user = models.ForeignKey(User)
    province = models.ForeignKey(Province)
    city = models.ForeignKey(City)
    district = models.ForeignKey(District)

当我知道 user_id 和 Province_id 时，如何删除关系？如果我使用 delete() 方法，它也会删除省，我想避免它。我在任何地方都找不到如何删除 m2m 字段中的 1 个特定关系。

Answer 1

在您的 ManyToMany 上使用 remove 方法经理。

Province.objects.get(id=3).user.remove(user_id)

如果您愿意，也可以直接访问直通表:

Province.user.through.objects.get(province__id=3, user__id=4).delete()