Django Object Manager Problem

Question

So here's a question for a Django wizard. I am inheriting an object Manager something along the lines as follows:

class MyObjManager(models.Manager):

    def total_values(self, myobj_id):
                return 49

    def what_the_heck(self, poll_id):
                return 48

class TestMe():

        def what_the_heck(self, poll_id):
               return 47

Now if I create a model that uses this object manager as follows it doesn't seem to work.

class MyObj(models.Model):
    x = models.CharField(max_length=200)
    y = models.DateTimeField('date published')
    objects = MyObjManager()
    kb = MyObjManager()
    testMe = TestMe()

    def total_values(self):  
     #A return self.objects.total_values(1)
            #B return self.objects.yyy(1) 
            #C return self.kb.what_the_heck(1)
            #D return 50
            #E return self.testMe.what_the_heck(1)
            #F return self.objects.what_the_heck(1)

Now suppose that A,B,C,D,E are commented out one at a time respectively. Here's the results if I call myObj.total_values. ( where myObj is instance of MyObj) A) Nothing B) Nothing C) Nothing D) 50 E) 47 F) Nothing

I've used two object managers in this example, but the same thing happens if I only use one. Any insights into why I can't seem to access the methods in my overriden object manager?

Answer 1

Is it unclear whether or not PollManager is actually inheriting from MyObjManager. Do you mean to call your class PollManager?

EDIT: You could try creating a constructor for MyObjManager. It would call Manager's constructor.

def __init__(self):
    models.Manager.__init__(self)

See if that works.

Answer 2

For A, B, and C, you cannot use self... that is a instance method, and self refers to that instance... which an instance doesn't have manager methods.

E and F work because, once again you are calling instance methods, of which you have properly declared the attributes.

For A, B, C, replace self with MyObj

class MyObj(models.Model):
    x = models.CharField(max_length=200)
    y = models.DateTimeField('date published')
    objects = MyObjManager()
    kb = MyObjManager()
    testMe = TestMe()

    def total_values(self):             
        #A return MyObj.objects.total_values(1)
        #B return MyObj.objects.yyy(1) 
        #C return MyObj.kb.what_the_heck(1)
        #D return 50
        #E return self.testMe.what_the_heck(1)
        #F return self.objects.what_the_heck(1)

I have a hard time thinking of a scenario where you would find an instance of the model, and then call a function on that to get other instances of that model, though... (I'm suggesting that your approach might be awkward or incorrect, stating your bigger scope problem might help you get a better answer.)