如何在mongodb中获取带有注释的所有文章？

Question

How do I grab all articles with comments? I have:

class Article
  include Mongoid::Document

  embeds_many :comments
end

class Comment
  include Mongoid::Document

  embedded_in :article
end

Answer 1

At the moment. This seems to work:

Article.where(:comments => {"$exists" => true})

Am I using the $exists directive correctly for this context?

Answer 2

存在评论的文章（因此，不是nil）

Article.where(:comments.ne => nil)