Django - 删除模型的所有相关外键

Question

我有一个名为 Team 的模型，与 Agent（我的用户模型）有一个 ForeignKey 关系。当team_leader 的代理停用团队时，所有将team_member 设置为当前团队的代理都将删除其team_member 属性并设置为NULL/空。

我读过this 和this，我知道我应该对._meta.get_fields() 或Collector 类做点什么。我正在尝试使用 get_fields()，但还没有成功。

models.py

class Agent(AbstractUser):
    team_member = models.ForeignKey('AgentTeam', on_delete=models.CASCADE, null=True, blank=True, related_name='team_member')
    team_leader = models.OneToOneField('AgentTeam', on_delete=models.CASCADE, null=True, blank=True, related_name='team_leader')

class AgentTeam(models.Model):
    team_is_active = models.BooleanField(default=False)

views.py

def deactivate_team(request):
    request.user.AgentTeam.team_is_active = False  # request.user in this case is the team_leader

    # I need to set all the Agent's with team_member set to the request.user's team to NULL.  I have experimented with the code below and gotten only errors, mostly related to ReverseToOne like ''ReverseManyToOneDescriptor' object is not iterable'
    agents = [
        f for f in AgentTeam._meta.get_fields()
        if (f.one_to_many)
        and f.auto_created and not f.concrete
    ]
    for agent in agents:
        objects = getattr(AgentTeam, agent.name).all()
        for object in objects:
            object.team_member = None

请在我的视图代码和我犯的任何错误上提供一些 cmets 和指针。谢谢。

Answer 1

如果我理解正确，我看不出您需要遍历模型字段的原因。

您可能无需费心处理模型的任何字段即可摆脱困境。当 AgentTeam 值为 null 时，您可以只更新所有代理的 team_member 状态。这可以在视图中完成，也可以在模型的 save() 方法中完成。例如：

class Agent(AbstractUser):
    team_member = models.ForeignKey('AgentTeam', on_delete=models.CASCADE, null=True, blank=True, related_name='team_member')
    team_leader = models.OneToOneField('AgentTeam', on_delete=models.CASCADE, null=True, blank=True, related_name='team_leader')

class AgentTeam(models.Model):
    team_is_active = models.BooleanField(default=False)

    def save(self, *args, **kwargs):
        super(AgentTeam, self).save(*args, **kwargs)
        if not self.team_is_active:
            Agent.objects.filter(
                team_member=self
            ).update(team_member=None)

然后在视图内：

def deactivate_team(request):
    team = request.user.AgentTeam
    team.team_is_active = False
    team.save()