Why a model instance accessed from a @property can't mutate?

Using Django Forms & APIs
1

Hello! I have the following code which I’ve been using for my test cases:

class MyAppTestCase(TestCase):

    @property
    def my_model(self) -> MyModel:
        return MyModel.objects.get(user=self.user)   # (self.user is defined in the setUp)

    def seed_models(self):
        self.my_model.attribute = 'hello'
        print(self.my_model.attribute)  # <- prints None

But, if I declare MyModel instance in the setUp like:

    def setUp(self):
        super().setUp()
        self.my_model = MyModel.objects.get(user=self.user)

Then I can make self.my_model mutate!

    def seed_models(self):
        self.my_model.attribute = 'hello'
        print(self.my_model.attribute)  # <- prints "hello"

Why does this behavior occur? I know Django queries are lazies, but can someone explain further?
My decision to access it from a @property was in order to always have an updated instance of MyModel (since this class is just an utility class to inherit in concrete test case classes)

2

That is the specific purpose and intent of the @property decorator. It creates a read-only attribute by that name in the class.

See the docs for more details.

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