def _delete_null_columns(self, conditionals=None):
        """
        executes a delete query to remove columns that have changed to null
        """
        ds = DeleteStatement(self.column_family_name, conditionals=conditionals, if_exists=self._if_exists)
        deleted_fields = False
        static_only = True
        for _, v in self.instance._values.items():
            col = v.column
            if v.deleted:
                ds.add_field(col.db_field_name)
                deleted_fields = True
                static_only &= col.static
            elif isinstance(col, columns.Map):
                uc = MapDeleteClause(col.db_field_name, v.value, v.previous_value)
                if uc.get_context_size() > 0:
                    ds.add_field(uc)
                    deleted_fields = True
                    static_only |= col.static

        if deleted_fields:
            keys = self.model._partition_keys if static_only else self.model._primary_keys
            for name, col in keys.items():
                ds.add_where(col, EqualsOperator(), getattr(self.instance, name))
            self._execute(ds)
def _delete_null_columns ( self , conditionals = None ) : ds = DeleteStatement ( self . column_family_name , conditionals = conditionals , if_exists = self . _if_exists ) deleted_fields = False static_only = True for _ , v in self . instance . _values . items ( ) : col = v . column if v . deleted : ds . add_field ( col . db_field_name ) deleted_fields = True static_only &= col . static elif isinstance ( col , columns . Map ) : uc = MapDeleteClause ( col . db_field_name , v . value , v . previous_value ) if uc . get_context_size ( ) > 0 : ds . add_field ( uc ) deleted_fields = True static_only |= col . static if deleted_fields : keys = self . model . _partition_keys if static_only else self . model . _primary_keys for name , col in keys . items ( ) : ds . add_where ( col , EqualsOperator ( ) , getattr ( self . instance , name ) ) self . _execute ( ds )
executes a delete query to remove columns that have changed to null