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

As mentioned, a correct alternative to implementing your own django.db.models.Field class, one should use - db_column argument and a custom (or hidden) class attribute. I am just rewriting the code in the edit by @Jiaaro following more strict conventions for OOP in python (e.g. if _foo should be actually hidden):

class MyModel(models.Model):
    __foo = models.CharField(max_length = 20, db_column='foo')
    bar = models.CharField(max_length = 20)

    @property
    def foo(self):
        if self.bar:
            return self.bar
        else:
            return self.__foo

    @foo.setter
    def foo(self, value):
        self.__foo = value

__foo will be resolved into _MyModel__foo (as seen by dir(..)) thus hidden (private). Note that this form also permits using of @property decorator which would be ultimately a nicer way to write readable code.

Again, django will create *_MyModel table with two fields foo and bar.