4
class Comment
include MongoMapper::Document
scope :by_rating, lambda { |minimum| where(:rating.gte => minimum) }
key :rating
belongs_to :user
end
class User
include MongoMapper::Document
many :comments
end
User.first.comments.by_rating(3)
最后一行的查询实际上做了什么? MongoMapper是否足够智能,只用两个WHERE条件(user_id和minimum rating)来执行一个查询?使用MongoMapper作用域查询关联的集合?