from django.db import models

from django.db.models.query_utils import DeferredAttribute

class CustomTypedField(models.TextField):

    def db_type(self, connection):

        return "custom_field"

class CustomDeferredAttribute(DeferredAttribute):

    def __get__(self, instance, cls=None):

        self._count_call(instance, "get")

        return super().__get__(instance, cls)

    def __set__(self, instance, value):

        self._count_call(instance, "set")

        instance.__dict__[self.field.attname] = value

    def _count_call(self, instance, get_or_set):

        count_attr = "_%s_%s_count" % (self.field.attname, get_or_set)

        count = getattr(instance, count_attr, 0)

        setattr(instance, count_attr, count + 1)

class CustomDescriptorField(models.CharField):

    descriptor_class = CustomDeferredAttribute