在Django中基于相关模型创建多个实例

Question

在大学里，作为项目的一部分，我们必须用Django开发一个liga系统。我有我的基本应用程序运行，我的模型也已经设置好了。

from django.db import models
from datetime import datetime

# Create your models here.
class Player(models.Model):
    vorname         = models.CharField(max_length=30)
    nachname        = models.CharField(max_length=50)
    created_on      = models.DateTimeField(auto_now_add=True)
    email           = models.EmailField()


class Liga(models.Model):
    name            = models.CharField(max_length=50)
    participants    = models.ManyToManyField(Player)
    created_on      = models.DateTimeField(auto_now_add=True)
    is_active       = models.BooleanField(default=False)
    is_completed    = models.BooleanField(default=False)

class Game(models.Model):
    liga            = models.ForeignKey(Liga, on_delete='DO NOTHING')
    player1         = models.CharField(max_length=100)
    player2         = models.CharField(max_length=100)
    score_pl1       = models.IntegerField(blank=True)
    score_pl2       = models.IntegerField(blank=True)
    is_completed    = models.BooleanField(default=False)
    completed_on    = models.DateTimeField(auto_now_add=True)

现在，当我在管理区域创建了一个新的liga时，我想让Django自动创建Game实例(可能是几个)。我尝试了几种不同的方法，但都不能解决这个问题。当我创建一个Liga实例时，我希望调用下面的方法。该方法创建一定数量的玩家的所有游戏。每一场比赛都应该通过游戏模型存储在数据库中。

player = ['Max', 'Sebastian', 'Tim', 'Bernd', 'Klaas', 'Kyle', 'Andreas', 'Jürgen']

def create_games(players):

    n = len(players)
    for i in range(0,n):
        print('--------------------------')
        print('Gameday ' + str(i+1))
        print('--------------------------')

        if i == len(players)-1:
            game = [players[i], players[0]]
        else:
            game = [players[i], players[n-1]]
        print(game)
        for k in range(1, n//2):
            game = [players[(i+k) % (n-1)], players[(i-k)%(n-1)]]
            print(game)
        print(' ')



liga1 = create_games(player)

Create_games的输出示例：

--------------------------
Gameday 1
--------------------------
['Max', 'Jürgen']
['Sebastian', 'Andreas']
['Tim', 'Kyle']
['Bernd', 'Klaas']

--------------------------
Gameday 2
--------------------------
['Sebastian', 'Jürgen']
['Tim', 'Max']
['Bernd', 'Andreas']
['Klaas', 'Kyle']

--------------------------
Gameday 3
--------------------------
['Tim', 'Jürgen']
['Bernd', 'Sebastian']
['Klaas', 'Max']
['Kyle', 'Andreas']

--------------------------
Gameday 4
--------------------------
['Bernd', 'Jürgen']
['Klaas', 'Tim']
['Kyle', 'Sebastian']
['Andreas', 'Max']

--------------------------
Gameday 5
--------------------------
['Klaas', 'Jürgen']
['Kyle', 'Bernd']
['Andreas', 'Tim']
['Max', 'Sebastian']

--------------------------
Gameday 6
--------------------------
['Kyle', 'Jürgen']
['Andreas', 'Klaas']
['Max', 'Bernd']
['Sebastian', 'Tim']

--------------------------
Gameday 7
--------------------------
['Andreas', 'Jürgen']
['Max', 'Kyle']
['Sebastian', 'Klaas']
['Tim', 'Bernd']

--------------------------
Gameday 8
--------------------------
['Jürgen', 'Max']
['Sebastian', 'Andreas']
['Tim', 'Kyle']
['Bernd', 'Klaas']

Answer 1

您可以在liga使用post_save信号(https://docs.djangoproject.com/en/2.2/ref/signals/#post-save)创建后调用此函数：

from django.db.models.signals import post_save
from django.dispatch import receiver

@receiver(post_save, sender=Liga)
def my_callback(sender, **kwargs):
    the_liga_created = kwargs.get('instance')
    print("Do whatever you want here; like calling create_games")

将这样的代码放在models.py或app_config ready函数中的模型定义之后是很常见的，通常在ready函数中导入一个名为signals.py的文件来连接信号，这是导入过程的一个副作用。