在django中处理通用关系的麻烦 [英] Trouble handling generic relationship in django

问题描述

我想模拟一个情况，我处理它真的很麻烦。域名是这样的：有帖子，每个帖子都必须与MediaContent一对一关联。 MediaContent可以是图片或视频（现在也许是以后的音乐）。所以，我有的是：

mediacontents / models.py

  class MediaContent（models.Model）：
 uploader = models.ForeignKey（User）
 title = models.CharField（max_length = 100）
 created = models.DateTimeField（auto_now_add = True）
 
 def draw_item（self）：
 pass 
 
 class Meta：
 abstract = True 
 
 class Picture（MediaContent） 
 picture = models.ImageField（upload_to ='pictures'）
 
 class Video（MediaContent）：
 identifier = models.CharField（max_length = 30）#youtube id 
  

posts / models.py

 code> class Post（models.Model）：
 ... 
＃link to MediaContent 
 content_type = models.ForeignKey（ContentType）
 object_id = models.PositiveIntegerField ）
 media_content = generic.GenericForeignKey（'content_type'，'object_id'）
  

最终想要做，可以调用方法，如：

  post1.media_content.draw_item（）
> > < iframe src =youtube.com...> 
 post2.media_content.draw_item（）
>> < img src =.../> 
  

这是正确的aproach，它是否正常工作？模板可以与下面的对象无关吗？

解决方案

您的方法对我来说看起来不错。您只需要覆盖图片和视频模型中的draw_item方法。您的模板将看起来像

  {％在帖子中的帖子％} 
 {{post.media_content.draw_item} } 
 {％endfor％} 
  

无论哪个模型是通用的外国人要点，只要它有一个 draw_item 方法定义。

I want to model a situation and I´m having real trouble handling it. The domain is like this: There are Posts, and every post has to be associated one to one with a MediaContent. MediaContent can be a picture or a video (for now, maybe music later). So, what I have is:

mediacontents/models.py

class MediaContent(models.Model):
    uploader = models.ForeignKey(User)
    title = models.CharField(max_length=100)
    created = models.DateTimeField(auto_now_add=True)

    def draw_item(self):
        pass

    class Meta:
        abstract = True

class Picture(MediaContent):
    picture = models.ImageField(upload_to='pictures')

class Video(MediaContent):
    identifier = models.CharField(max_length=30) #youtube id

posts/models.py

class Post(models.Model):
    ...
    # link to MediaContent
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    media_content = generic.GenericForeignKey('content_type', 'object_id')

What i eventually want to do, is beeing able to call methods like:

post1.media_content.draw_item()
>> <iframe src="youtube.com" ...>
post2.media_content.draw_item()
>> <img src="..."/>

Is this the correct aproach, does it work? Can the template be agnostic of the object underneath?

解决方案

Your approach looks good to me. You just need to override the draw_item method in your Picture and Video models. Your template will look something like

{% for post in posts %}
  {{ post.media_content.draw_item }}
{% endfor %}

and it doesn't matter which model the generic foreign key points to, as long as it has a draw_item method defined.

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