rails presence

api详细介绍了 presence

object.present? ? object : nilFor example, something likestate   = params[:state]   if params[:state].present?country = params[:country] if params[:country].present?region  = state || country || 'US'

下面的一样

region = params[:state].presence || params[:country].presence || 'US'

详细解释

def presence  self if present?enddef present?  !blank?end