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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
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