Return display_name in ChoiceField

I'm implementing some REST API in DRF with ModelViewSet and ModelSerializer. All my APIs use the JSON format and some of my models use ChoiceField field, like that:

MyModel(models.Model):
     KEY1 = 'Key1'
     KEY2 = 'Key2'
     ATTRIBUTE_CHOICES = (
         (KEY1, 'Label 1'),
         (KEY2, 'Label 2'))
     attribute = models.CharField(max_length=4, 
                                  choices=ATTRIBUTE_CHOICES, default=KEY1)

My problem is that by default DRF always returns (and accept) the key of these choices for JSON messages (see here), but I would like to use the label instead, because I think it's more consistent and clear to unterstand for who will use those APIs. Any suggestion?

I found a possible solution, namely defining my own field as follow:

class MyChoiceField(serializers.ChoiceField):

    def to_representation(self, data):
        if data not in self.choices.keys():
            self.fail('invalid_choice', input=data)
        else:
            return self.choices[data]

    def to_internal_value(self, data):
        for key, value in self.choices.items():
            if value == data:
                 return key
        self.fail('invalid_choice', input=data)

It works the same way as to ChoiceField, but returns and accepts labels instead of keys.