overwrite field value in subclasses

[Emmanuel Jannetti]

Hi all,

One piece of my model is as follow :

class UpperAbstract(models.Model):

  CHOICE_A = 0

  CHOICE_B = 1

  CHOICE_C = 2

  myfield = models.PositiveSmallIntegerField(choices=((CHOICE_A,'A'),(CHOICE_B,"B"),(CHOICE_C,"C")),blank=False)

  class Meta:

abstract = True

class Foo(UpperAbstract):

      myfield = UpperAbstract.CHOICE_A

I am expecting any instance of Foo being created, to have 'myfield' always and "automatically" set to UpperAbstract.CHOICE_A

In my test the created object as null value and saving it is refused on IntegrityError because 'myfield' cannot be None

thank in advance for any help.

regards

manu

[Peter of the Norse]

Foo.myfield is 0, but when you created a new models.Field object in the abstract class, it did some deep magic. There’s also Foo._meta.fields which has the old myfield in it. The only thing you can do is create a new myfield with default=0 and editable=False.

Peter of the Norse
Rahm...@Radio1190.org

[Emmanuel Jannetti]

Hi,

Thank for the reply.

Digging into _meta.fields of a created instance I see, as you said that myfield is still defined as in the upper class.

If I understood correctly your answer sub-class should have the field "redefine" instead of assigned .

something like 

myfield = models.PositiveSmallIntegerField(editable=False,default=UpperAbstract.CHOICE_A)

doing this , model validation raise a fieldRerror exception arguing that I am not allowed to do that because a field with the same

name already exists.

Did I misunderstood your comment ?

thx

manu

[Emmanuel Jannetti]

Hi,

checking on my side.

All this works as soon as upper class are not abstract.

regards 

manu