python - Django 在创建另一个对象时创建并保存模型的许多实例

Question

我正在设计一个国际象棋游戏，我想在新的 ChessParty 开始后用棋子(状态模型)初始化字段。
我阅读了有关覆盖 save() 模型方法的信息，但我不知道如何在我的案例中使用它。
我正在阅读有关 post_save 之类的信号，但我遇到了同样的问题。

这样的东西能行吗？

    def save(self, *args, **kwargs):
        (Here i want create many instances of another Model)
    super(ChessParty, self).save(*args, **kwargs)

到目前为止，这是我的代码:

class ChessParty(models.Model):
    chessparty_id = models.AutoField("ID partii", primary_key=True)
    arbiter = models.ForeignKey(Arbiter, related_name='sedzia', 
    verbose_name="Sędzia")
    white = models.ForeignKey(Player, related_name='Białe', 
    verbose_name="Białe figury")
    black = models.ForeignKey(Player, related_name='Czarne', 
    verbose_name="Czarne figury")
    tournament = models.ForeignKey(Tournament, verbose_name="Nazwa turnieju")

    def __str__(self):
        return "{white} vs {black}, ({tournament})"\
            .format(black=self.black, white=self.white, tournament=self.tournament)


class OneMove(models.Model):
party = models.ForeignKey(ChessParty, default='0', verbose_name="Partia")
chessman = (
    ('a1_w_rook', 'biała wieża a1'), ('h1_w_rook', 'biała wieża h1'),
    ('b1_w_knight', 'biały skoczek b1'), ('g1_w_knight', 'biały skoczek g1'),
    ('c1_w_bishop', 'biały goniec c1'), ('f1_w_bishop', 'biały goniec f1'),
    ('d1_w_queen', 'biały hetman d1'), ('e1_w_king', 'biały król e1'),
    ('a2_w_pawn', 'biały pion a2'), ('b2_w_pawn', 'biały pion b2'),
    ('c2_w_pawn', 'biały pion c2'), ('d2_w_pawn', 'biały pion d2'),
    ('e2_w_pawn', 'biały pion e2'), ('f2_w_pawn', 'biały pion f2'),
    ('g2_w_pawn', 'biały pion g2'), ('h2_w_pawn', 'biały pion h2'),
    ('a8_b_rook', 'czarna wieża a1'), ('h8_b_rook', 'czarna wieża h8'),
    ('b8_b_knight', 'czarny skoczek b1'), ('g8_b_knight', 'czarny skoczek g8'),
    ('c8_b_knight', 'czarny goniec c1'), ('f8_b_bishop', 'czarny goniec f8'),
    ('d8_b_queen', 'czarny hetman d1'), ('e8_b_king', 'czarny król e8'),
    ('a7_b_pawn', 'czarny pion a7'), ('b7_b_pawn', 'czarny pion b7'),
    ('c7_b_pawn', 'czarny pion c7'), ('d7_b_pawn', 'czarny pion d7'),
    ('e7_b_pawn', 'czarny pion e7'), ('f7_b_pawn', 'czarny pion f7'),
    ('g7_b_pawn', 'czarny pion g7'), ('h7_b_pawn', 'czarny pion h7'),
 )
chessman = models.CharField(max_length=30, choices=chessman, default='pionek', verbose_name="Figura Szachowa")
mymove = []
for a, b in itertools.product('abcdefgh', '12345678'):
    name = a + b
    mymove.append((name, name))
mytuple = tuple(mymove)
move = models.CharField(max_length=2, choices=mytuple, default='a1', verbose_name="Ruch na")

class Meta:
    abstract = True


class State(OneMove):
state_id = models.PositiveIntegerField(default=0, verbose_name="numer ruchu")
is_capture = models.BooleanField(default=False, verbose_name="Czy zbita")
capture_choice = (
    ('true', 'zbity'),
    ('false', 'nie zbity'),
)
is_capture = models.CharField(max_length=9, choices=capture_choice, default='false', verbose_name="Czy zbity")

Answer 1

使用save():

如果您想使用save() 方法，您可以执行以下操作:

def save(self, *args, **kwargs):
    OtherModel.objects.create(something=kwargs['something'])
    YetAnotherModel.objects.create(
        something_else=kwargs['something_else']
    )
    super(ChessParty, self).save(*args, **kwargs)

正如@e4c5 在他的评论中所说，它更容易实现，这就是我将它包括在内的原因!

---

我对这个问题的看法:

尽管您可以在 save() 上执行此操作，但我建议改为使用 signal .

具体使用一个post_save信号。以下是如何做到这一点:

1. 创建文件 your_app/signals.py:

   from django.db.models.signals import post_save
   from django.dispatch import receiver
   
   from your_app.models import ChessParty, OtherModel, YetAnotherModel
   
   
   @receiver(post_save, sender=ChessParty)
   def change_my_name_plz (sender, instance, created, **kwargs):
       if created:
           OtherModel.objects.create(something=kwargs['something'])
           YetAnotherModel.objects.create(
               something_else=kwargs['something_else']
           )
   

2. 您现在需要覆盖 your_app/app.py 上的 ready() 函数:

   from django.apps import AppConfig
   
   class YourAppConfig(AppConfig):
       name = 'your_project.your_app'
   
       def ready(self):
           import your_project.your_app.signals
   

3. 最后，在your_app/__init__.py中添加以下内容:

   default_app_config = 'your_project.your_app.apps.YourAppConfig'
   

现在您有一个信号，它将在您创建一个新的 ChessParty 对象后立即创建一个 OtherModel 和 YetAnotherModel 对象。

---

定义信号的替代方法:

还有一种替代方法不使用 @receiver 装饰器，而是使用 connect()方法:

1. your_app/signals.py:

   from your_app.models import ChessParty, OtherModel, YetAnotherModel
   
   
   def change_my_name_plz (sender, instance, created, **kwargs):
       if created:
           OtherModel.objects.create(something=kwargs['something'])
           YetAnotherModel.objects.create(
               something_else=kwargs['something_else']
           )
   

2. your_app/app.py:

   from django.apps import AppConfig
   from django.db.models.signals import post_save
   
   from your_app.models import ChessParty
   from your_project.your_app.signals import change_my_name_plz
   
   class YourAppConfig(AppConfig):
       name = 'your_project.your_app'
   
       def ready(self):
           post_save.connect(change_my_name_plz, sender=ChessParty)
   

3. your_app/__init__.py 与上面相同(第 3 步)。

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