How to get the app a Django model is from?

问题:

I have a model with a generic relation:

TrackedItem --- genericrelation ---> any model

I would like to be able to generically get, from the initial model, the tracked item.

I should be able to do it on any model without modifying it.

To do that I need to get the content type and the object id. Getting the object id is easy since I have the model instance, but getting the content type is not: ContentType.object.filter requires the model (which is just content_object.__class__.__name__) and the app_label.

I have no idea of how to get in a reliable way the app in which a model is.

For now I do app = content_object.__module__.split(".")[0], but it doesn't work with django contrib apps.

回答1:

You don't need to get the app or model just to get the contenttype - there's a handy method to do just that:

ContentType.objects.get_for_model(myobject)

Despite the name, it works for both model classes and instances.

回答2:

The app_label is available as an attribute on the _meta attribute of any model.

from django.contrib.auth.models import User
print User._meta.app_label
# The object name is also available
print User._meta.object_name

回答3:

You can get both app_label and model from your object using the built-in ContentType class

from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import User

user_obj = User.objects.create()
obj_content_type = ContentType.objects.get_for_model(user_obj)

print(obj_content_type.app_label)
# u'auth'
print(obj_content_type.model)
# u'user'

This is a better approach respect of using the _meta properties that are defined as private.