为什么需要在Django admin中同时注册应用名称和应用管理员名称？

Question

I am trying to understand why, when adding a custom Admin site for a django app, one needs to add both the model and the admin function. Say, you have an application called Story , and thus the admin site will be called StoryAdmin . When registering this on the django administration interface, you need to add this line:

# Registering all the changes to admin.site
admin.site.register(Story, StoryAdmin)

My question is, is there a way to just do this:

admin.site.register(StoryAdmin)

Adding only one thing, not two, because this makes things simpler, and there is a smaller chance for an error, and the code just looks less redundant. It would make things look much better, because in the end, you could have a clean list of all the admin panels:

admin.site.register(
    StoryAdmin,
    SomeAdmin,
    FooAdmin,
)

Answer 1

That's not how admin.site.register is built . It expects a Model and then optionally the ModelAdmin with which to display that Model:

def register(self, model_or_iterable, admin_class=None, **options):
    """
    Registers the given model(s) with the given admin class.

    The model(s) should be Model classes, not instances.

    If an admin class isn't given, it will use ModelAdmin (the default
    admin options). If keyword arguments are given -- e.g., list_display --
    they'll be applied as options to the admin class.

    If a model is already registered, this will raise AlreadyRegistered.

    If a model is abstract, this will raise ImproperlyConfigured.
    """

This allows you to use the same ModelAdmin on multiple Models (which can be desirable when, for example, you subclass a model off the same abstract Model).

It doesn't suit your style but it's just one of those things you just have to accept and get on with.

Answer 2

That's a good question, it could have been designed that way, but that's not the case.

I asume the main reason is to allow the admin class to be optional and use the default base ModelAdmin class for simple cases and to allow to use the same ModelAdmin subclass with many models , see implementation at: https://github.com/django/django/blob/master/django/contrib/admin/sites.py#L52-101

Also you don't need to define the class yourself if you need to customize a ModelAdmin, you can just pass kwargs to the register function:

admin.site.register(Story, list_display=['field1', 'field2'])

So that's my bet, they try to minimize the boilerplate when registering a model and allow it to be more flexible.