root?()
Returns true is this is a root node.
# File activerecord/lib/active_record/acts/nested_set.rb, line 120 def root? parent_id = self[parent_column] (parent_id == 0 || parent_id.nil?) && (self[left_col_name] == 1) && (self[right_col_name] > self[left_col_name]) end