                  val = getattr(instance, self.field_name)
              data[self.field_name] = val
          return data[self.field_name]
  
      def __set__(self, instance, value):
          """
          Deferred loading attributes can be set normally (which means there will
          never be a database lookup involved.
          """
          instance.__dict__[self.field_name] = value
  
      def _check_parent_chain(self, instance, name):
          """
          Check if the field value can be fetched from a parent field already
          loaded in the instance. This can be done if the to-be fetched
          field is a primary key field.
 
</s> remove # This function is needed because data descriptors must be defined on a class
# object, not an instance, to have any effect.

def deferred_class_factory(model, attrs):
    """
    Returns a class object that is a copy of "model" with the specified "attrs"
    being replaced with DeferredAttribute objects. The "pk_value" ties the
    deferred attributes to a particular instance of the model.
    """
    if not attrs:
        return model
    opts = model._meta
    # Never create deferred models based on deferred model
    if model._deferred:
        # Deferred models are proxies for the non-deferred model. We never
        # create chains of defers => proxy_for_model is the non-deferred
        # model.
        model = opts.proxy_for_model
    # The app registry wants a unique name for each model, otherwise the new
    # class won't be created (we get an exception). Therefore, we generate
    # the name using the passed in attrs. It's OK to reuse an existing class
    # object if the attrs are identical.
    name = "%s_Deferred_%s" % (model.__name__, '_'.join(sorted(attrs)))
    name = utils.truncate_name(name, 80, 32)

    try:
        return opts.apps.get_model(model._meta.app_label, name)

    except LookupError:

        class Meta:
            proxy = True
            apps = opts.apps
            app_label = opts.app_label

        overrides = {attr: DeferredAttribute(attr, model) for attr in attrs}
        overrides["Meta"] = Meta
        overrides["__module__"] = model.__module__
        overrides["_deferred"] = True
        return type(str(name), (model,), overrides)


 </s> add  </s> remove         if self.model._deferred:
            # Deferred model will not be found from the app registry. This
            # could be fixed by reconstructing the deferred model on unpickle.
            raise RuntimeError("Fields of deferred models can't be reduced")
 </s> add  </s> remove ``field_names`` are in the same order as the ``values``, so it is possible to
use ``cls(**(zip(field_names, values)))`` to instantiate the object. If all
of the model's fields are present, then ``values`` are guaranteed to be in
the order ``__init__()`` expects them. That is, the instance can be created
by ``cls(*values)``. It is possible to check if all fields are present by
consulting ``cls._deferred`` - if ``False``, then all fields have been loaded
from the database.
 </s> add ``field_names`` are in the same order as the ``values``. If all of the model's
fields are present, then ``values`` are guaranteed to be in the order
``__init__()`` expects them. That is, the instance can be created by
``cls(*values)``. If any fields are deferred, they won't appear in
``field_names``. In that case, assign a value of ``django.db.models.DEFERRED``
to each of the missing fields. </s> remove         if not self._deferred:
            class_id = self._meta.app_label, self._meta.object_name
            return model_unpickle, (class_id, [], simple_class_factory), data
        defers = []
        for field in self._meta.fields:
            if isinstance(self.__class__.__dict__.get(field.attname),
                          DeferredAttribute):
                defers.append(field.attname)
        model = self._meta.proxy_for_model
        class_id = model._meta.app_label, model._meta.object_name
        return (model_unpickle, (class_id, defers, deferred_class_factory), data)
 </s> add         class_id = self._meta.app_label, self._meta.object_name
        return model_unpickle, (class_id,), data
                  val = getattr(instance, self.field_name)
              data[self.field_name] = val
          return data[self.field_name]
  







      def _check_parent_chain(self, instance, name):
          """
          Check if the field value can be fetched from a parent field already
          loaded in the instance. This can be done if the to-be fetched
          field is a primary key field.
keep keep keep keep replace replace replace replace replace replace replace keep keep keep keep keep
 Fixed #26207 -- Replaced dynamic classes with non-data descriptors for deferred instance loading. 
django/db/models/query_utils.py