  are loaded from the database::
  
      @classmethod
      def from_db(cls, db, field_names, values):
          # default implementation of from_db() (could be replaced
          # with super())
          if cls._deferred:
              instance = cls(**zip(field_names, values))
          else:
              instance = cls(*values)
          instance._state.adding = False
          instance._state.db = db
          # customization to store the original field values on the instance
          instance._loaded_values = dict(zip(field_names, values))
          return instance
 
</s> remove         if cls._deferred:
            new = cls(**dict(zip(field_names, values)))
        else:
            new = cls(*values)
 </s> add         if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [values.pop() if f.attname in field_names else DEFERRED for f in cls._meta.concrete_fields]
        new = cls(*values) </s> remove         non_deferred_model = instance._meta.proxy_for_model
        opts = non_deferred_model._meta

        assert instance is not None
 </s> add         if instance is None:
            return self
        opts = instance._meta </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     _deferred = False
 </s> add 
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
  are loaded from the database::
  
      @classmethod
      def from_db(cls, db, field_names, values):
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
        # Default implementation of from_db() (subject to change and could
        # be replaced with super()).
        if len(values) != len(cls._meta.concrete_fields):
            values = list(values)
            values.reverse()
            values = [
                values.pop() if f.attname in field_names else DEFERRED
                for f in cls._meta.concrete_fields
            ]
        new = cls(*values)
          instance._state.adding = False
          instance._state.db = db
          # customization to store the original field values on the instance
          instance._loaded_values = dict(zip(field_names, values))
          return instance
keep keep keep keep replace replace replace replace replace replace keep keep keep keep keep
 Fixed #26207 -- Replaced dynamic classes with non-data descriptors for deferred instance loading. 
docs/ref/models/instances.txt