Validate object attribute in manager in Django

Question

I have a manager in which I have

class MyManager(models.Manager):
    TYPE_PENDING = 1

    def pending():
        return self.filter(type=self.TYPE_PENDING)

Now I can always get a queryset of pending objects.

But can I also do something to check if an object is pending?

I can of course use if object.type == MyManager.TYPE_PENDING: but can I do something in the manager, so I don't have to call MyManager.TYPE_PENDING outside the manager but instead create a function like

def is_pending():
    return self.type == self.TYPE_PENDING

or something like that.

I could also do something like if object in Model.objects.pending(): but doesn't it have bad performance since it loads the entire queryset?

Edit

If I have two managers PackageManager and StateManager related to models Package and State, resp.

class PackageManager(models.Manager):
    def delivered(self):
        return self.filter(current_state__type=1)

class StateManager(models.Manager):
    def delivered(self):
        return self.filter(type=self.model.TYPE_DELIVERED)

I have my choices (TYPE_DELIVERED etc.) defined in State. Can I in PackageManager replace 1 with something telling that it should be TYPE_DELIVERED?

I know I can write current_state__type=State.TYPE_DELIVERED but it causes a circular import if I should import managers into models and models into managers.

Can I utilize that I can get a State queryset filtering for all delivered?

I mean if I can do something like

class PackageManager(models.Manager):
    def delivered(self):
        return self.filter(current_state__type=StateManager.model.TYPE_DELIVERED)

Answer 1

I think it would be more appropriate to define TYPE_PENDING in the model itself:

class MyModel(models.Model):
    TYPE_PENDING = 1
    ...

    @property
    def is_pending(self):
        return self.type == self.TYPE_PENDING

    objects = MyManager()

...

class MyManager(models.Manager):
    def pending():
        return self.filter(type=self.model.TYPE_PENDING)