Django 应用程序依赖循环 [英] Django App Dependency Cycle

问题描述

我正在开发一个 Django 应用程序，该应用程序具有相当复杂的模型(它为一所大学建模 - 课程、模块、讲座、学生等)

I am in the middle of developing a Django application, which has quite complicated models (it models a university - courses, modules, lectures, students etc.)

我已将项目分成应用程序，以使整个事情更有条理(应用程序是课程、学校、人员、模块和时间段).我遇到了一个问题，一个应用程序中的模型可能依赖于另一个应用程序中的模型 - 所以我必须导入它.然后第二个应用又依赖于第一个中的模型，因此有一个循环，Python 会抛出一个错误.

I have separated the project into apps, to make the whole thing more organised (apps are courses, schools, people, modules and timeperiods). I am having a problem whereby a model in one app may depend on a model in another - so I must import it. The second app then in turn depends on a model in the first, so there is a cycle and Python throws up an error.

人们如何处理这个问题?我知道应用程序应该相对独立"，但在这样的系统中，使用 ContentTypes 将学生链接到模块是没有意义的.

How do people deal with this? I understand that apps should be relatively "independent", but in a system like this it doesn't make sense, for example, to use ContentTypes to link students to a module.

有没有人有类似的项目可以评论这个案例?

Does anyone have a similar project that could comment on this case?

推荐答案

如果您的依赖关系是外键引用其他应用程序中的模型，您不需要导入其他模型.您可以在 ForeignKey 定义中使用字符串:

If your dependency is with foreign keys referencing models in other applications, you don't need to import the other model. You can use a string in your ForeignKey definition:

class MyModel(models.Model):
    myfield = models.ForeignKey('myotherapp.MyOtherModel')

这样就不需要导入MyOtherModel，所以没有循环引用.Django 在内部解析字符串，一切都按预期工作.

This way there's no need to import MyOtherModel, so no circular reference. Django resolves the string internally, and it all works as expected.

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