如何为一个对象建模许多blob？ [英] How to model many blobs for an object?

问题描述

我想在文本对象和blob之间启用类似于一对多关系的东西，以便文本对象（文章或类似文件）具有许多图像和/或视频。有两种方法可以看到如何在第一种方法中使用blob列表作为实例变量。

I want to enable something like a one-to-many relation between a text object and blobs so that a text object (an "article" or likewise) has many images and/or videos. There are two ways I see how to do this where the first is using a list of blobs as instance variable. Will it work?

class A(search.SearchableModel):
  blobs = db.ListProperty(blobstore.BlobReferenceProperty())

优点：只需一个班级。易于读取和设置数据。
缺点：缺少额外的blob信息，例如如果我想用描述性词语来标记blob，我仍然需要两个类：

Advantages: Just one class. Readable and easy to get and set data. Disadvantages: Lacks extra info for blobs e.g. if I want to tag a blob with descriptive words I still need two classes instead:

class A(search.SearchableModel):
...
class B(db.Model):
  reference=db.ReferenceProperty(A,collection_name='matched_blobs',verbose_name="Title")
  blob = blobstore.BlobReferenceProperty()

后面的例子有一个缺点，因为它需要引用属性并引入2个类，可以像第一个例子一样只用A类来解决。后面的解决方案的优点是，它明确记录，而blobreferenceproperties的列表属性不是，我已经实现了后来的解决方案，现在我正在考虑使用blob列表而不是引用集合。它是否重要，或者两者都工作得相当好？你可以推荐哪种方式选择，如果有这些或其他吗？

The later example has a disadvantage since it requires a referenceproperty and introduces 2 classes where the problem could be solved with just class A as in the first example. The advantage of the later solution is that it's clearly documented while a listproperty of blobreferenceproperties isn't and the later solution I already have implemented and now I'm thinking about using a list of blobs instead of a referenced collection. Does it matter or will both work rather equally well? Can you recommend which way to choose, if any of these or another?

谢谢

Thanks

推荐答案

App Engine在他们的文档中实际上有一篇文章： http：/ /code.google.com/appengine/articles/modeling.html

App Engine actually has an article on this in their documentation: http://code.google.com/appengine/articles/modeling.html

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