Django model inheritance and type check

Question

class Machine(models.Model):
    name= models.CharField( max_length=120)
    class Meta:
        abstract = True

class Car(Machine):
    speed = models.IntegerField()

class Computer(Machine)
    ram = models.IntegerField()

My question is, how can I understand what type is the Machine model. For instamce I know the incoming query is a children of the Machine model but I also want to know it is a Car submodel.

Answer 1

I am not sure if I understand your question correctly. If you are trying to find out the type of a given instance you can use the built-in type function.

an_object = Car(name = "foo", speed = 80)
an_object.save()
type(an_object) # <class 'project.app.models.Car'>

Or if you wish to check if an_object is an instance of Car you can use isinstance.

isinstance(an_object, Car) # True

Answer 2

isinstance would work only if you fetched the object calling the Car class. if you do Machine.objects.all() and later want to know if is a car, what you can do is use hasattr. like:

o = Machine.objects.all()[0]
print(hasattr(o, 'car'))