sql - 我应该如何建模模型可以与 Django 中不同类型的实体相关的模式

Question

架构选项 1:https://gist.github.com/guyjacks/6ec4c1b0fa41b3f666f5c6adf2dfaf89

架构选项 2:https://gist.github.com/guyjacks/4838cd76b2f924629d2a3f2ba316a504

我想这实际上是两个问题:

1. 从关系数据库的角度推荐哪种架构？
2. 在 Django 中是否有一种惯用的方法来对任一模式进行建模？

干杯!

Answer 1

一种方法是使用Generic Relations:

from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType

在模型中你想关联各种模型:

class SomeModel(models.Model):
    ...

    # Below the mandatory fields for generic relation
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey()

在你想要相关的模型中:

from django.contrib.contenttypes.fields import GenericRelation

class SomeOtherModel(models.Model):
    ...
    # The relation
    your_field = GenericRelation(SomeModel)

如果您希望能够使用反向查询，请从文档中查看:

related_query_name

The relation on the related object back to this object doesn’t exist by default. Setting related_query_name creates a relation from the related object back to this one. This allows querying and filtering from the related object.

使用它们时应小心，因为它们会迅速增加复杂性。

更多信息链接:

https://docs.djangoproject.com/en/1.11/ref/contrib/contenttypes/#generic-relations https://simpleisbetterthancomplex.com/tutorial/2016/10/13/how-to-use-generic-relations.html