Django 与从父模型继承的模型的关系

Question

我在 django 中有 4 个模型，这里有 3 个（第 4 个是默认用户模型）：

class Post(models.Model):
    title = CharField(max_length=200)
    content = TextField()

    def __str__(self):
        return self.title


class NewsArticle(Post):
    link = URLField(default='')
    external_id = CharField(unique=True,
                            max_length=50, help_text='The ID of the news article from the source')
    source = CharField(max_length=15, help_text='Name of source website')

class Like(models.Model):
    LIKE_CHOICES = [('L', 'Like'), ('D', 'Dislike')]

    user = ForeignKey(User, on_delete=models.CASCADE)
    post = ForeignKey(Post, on_delete=models.CASCADE, related_name='post')
    state = CharField(default='L', max_length=1, choices=LIKE_CHOICES)
    created_at = DateTimeField(auto_now_add=True)
    updated_at = DateTimeField(auto_now=True)

    def __str__(self):
        return self.get_state_display()

据我了解，这样新闻文章根本不会与点赞相关联。我的目标是获取所有新闻文章和select_related() 的点赞。我也不想为喜欢的新闻文章创建一个新模型。我可以在这里做什么？

Answer 1

内容类型就是答案！ https://docs.djangoproject.com/en/3.0/ref/contrib/contenttypes/

由于您的 Post 类只是其他模型的基础，您应该将其标记为抽象，因此 Django 首先不会在数据库中为其创建表：

class Post(models.Model):
  class Meta:
    abstract = True

  title = CharField(max_length=200)
  content = TextField()

  def __str__(self):
    return self.title

在您的 NewsArticle 类中：

class NewsArticle(Post):
  link = URLField(default='')
  external_id = CharField(unique=True, max_length=50, help_text='The ID of the news article from the source')
  source = CharField(max_length=15, help_text='Name of source website')
  likes = GenericRelation(Like)

在你的 Like 类中：

class Like(models.Model):
  LIKE_CHOICES = [('L', 'Like'), ('D', 'Dislike')]

  user = ForeignKey(User, on_delete=models.CASCADE)
  state = CharField(default='L', max_length=1, choices=LIKE_CHOICES)
  created_at = DateTimeField(auto_now_add=True)
  updated_at = DateTimeField(auto_now=True)

  content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
  object_id = models.PositiveIntegerField()
  content_object = GenericForeignKey('content_type', 'object_id')

  def __str__(self):
    return self.get_state_display()