是否根据相同型号ForeignKey字段中的选择过滤管理窗体中的ManytoMany选项？

Question

我正在创建一个"matches“模型，该模型当前包含以下字段：

event = models.ForeignKey(Event, on_delete=models.RESTRICT)
match_participants = models.ManyToManyField(Wrestler, on_delete=models.RESTRICT, null=True, blank=True,)
match_type = models.CharField(max_length=25, choices=match_choices, default=BLOCK)
match_result = models.CharField(max_length=25, choices=result_choices, default=NOT_OC)
winner = models.ForeignKey(Wrestler, on_delete=models.RESTRICT, null=True, blank=True, related_name="winner")

在我的场景中，" winner“只能是"match_participants”中选择的外键之一，我真的希望将winner字段过滤到那些选择的外键。这个是可能的吗？我知道你可以根据其他模型中的条目来过滤外键选择，但对相同的表条目就不太确定了。

下面是我的数据库结构的UML示例：

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Answer 1

您可以在ManytoMany关系中添加额外的字段

https://docs.djangoproject.com/en/2.2/topics/db/models/#extra-fields-on-many-to-many-relationships

models.py

class Match(models.Model):
    wrestlers = models.ManyToManyField(Wrestler, through='Participation' )
    ...



class Participation(models.Model):
    wrestler = models.ForeignKey(Wrestler, on_delete=models.CASCADE)
    match = models.ForeignKey(Match, on_delete=models.CASCADE)
    winner = models.BooleanField()

然后，对于验证，您可以使用信号连接到参与更新，例如

def match_wrestlers_changed(sender, *args, **kwargs):
    if invalid:
        raise ValidationError('There already a winner.')

m2m_changed.connect(
    match_wrestlers_changed,
    sender=Match.wrestlers.through)