gistfile1.rb

> tagging = Tagging.create(:post => Post.first, :tag => Tag.first)
(rdb:1) irb
irb(...):001:0> klass
=> Tagging(id: integer, tag_id: integer, post_id: integer, created_at: datetime, updated_at: datetime)
irb(...):002:0> attribute
=> :tag
irb(...):004:0> klass.columns_hash.keys
=> ["id", "tag_id", "post_id", "created_at", "updated_at"]