Django: override get_FOO_display()

Normally you would just override a method as you have shown. But the trick here is that the get_FOO_display method is not present on the superclass, so calling the super method will do nothing at all. The method is added dynamically by the field class when it is added to the model by the metaclass - see the source here (EDIT: outdated link as permalink).

One thing you could do is define a custom Field subclass for your unit field, and override contribute_to_class so that it constructs the method you want. It's a bit tricky unfortunately.

(I don't understand your second question. What exactly are you asking?)

Now in Django > 2.2.7:

Restored the ability to override get_FOO_display() (#30931).

You can override:

    class FooBar(models.Model):
        foo_bar = models.CharField(_("foo"),  choices=[(1, 'foo'), (2, 'bar')])
    
    
   
        def get_foo_bar_display(self):
            return "something"