do properties work on django model fields?

Question

I think the best way to ask this question is with some code... can I do this? (edit: ANSWER: no)

class MyModel(models.Model):    
    foo =          


        

Answer 1

The previous solutions suffer because @property causes problems in admin, and .filter(_foo).

A better solution would be to override setattr except that this can cause problems initializing the ORM object from the DB. However, there is a trick to get around this, and it's universal.

class MyModel(models.Model):
    foo = models.CharField(max_length = 20)
    bar = models.CharField(max_length = 20)

    def __setattr__(self, attrname, val):
        setter_func = 'setter_' + attrname
        if attrname in self.__dict__ and callable(getattr(self, setter_func, None)):
            super(MyModel, self).__setattr__(attrname, getattr(self, setter_func)(val))
        else:
            super(MyModel, self).__setattr__(attrname, val)

    def setter_foo(self, val):
        return val.upper()

The secret is 'attrname in self.__dict__'. When the model initializes either from new or hydrated from the __dict__!