validation default null for database default null fields

Hi Yii Team,

If I have table fields that are declared to have its default to NULL, why not include the ‘default’ in the rules when generating a model via gii? Something like

array('columns_which_are_default_NULL', 'default', 'setOnEmpty' => true, 'value' => NULL)

should be seen when generating the model.

If this has been requested already, then consider this as a followup.

If was already declined, kindly enlighten me why. Because I am now tinkering my gii model generator now. :D

Good idea for 2.0, I think.