如何查找符合我标准的所有文档,与文档嵌入的深度无关?
假设我有一个使用* recursively_embeds_many *的模型。例如,可以回复的评论。回复,可以有另一个回复等等。
class Comment
include Mongoid::Document
field :content, type: String
recursively_embeds_many # this makes comment.child_comments available
end
所以结构基本上是:
如何查询内容等于“foo”的所有评论文档?
答案 0 :(得分:3)
此解决方案使用Mongodb点表示法查询与$or
组合来提取相关注释,然后遍历它们。您必须指定最大递归级别。
请不要在现场制作中使用任何东西!如果您使数据库崩溃,我不想要负责:P
# app/models/comment.rb
class Comment
include Mongoid::Document
field :content, type: String
recursively_embeds_many # this makes comment.child_comments available
# 'n' is the maximum level of recursion to check.
def self.each_matching_comment(n, q, &block)
queries = 0.upto(n).collect { |l| level_n_query(l, q) }
Comment.or(*queries).each { |c| c.each_matching_subcomment(q, &block) }
end
def self.level_n_query(n, q)
key = (['child_comments'] * n).join('.') + 'content'
return {key => q}
end
# recursive, returns array of all subcomments that match q including self
def each_matching_subcomment(q, &block)
yield self if self.content == q
self.child_comments.each { |c| c.each_matching_subcomment(q, &block) }
end
end
# hits each comment/subcomment up to level 10 with matching content once
Comment.each_matching_comment(10, 'content to match') do |comment|
puts comment.id
end
如果您希望这样做更快,您应该在评论和子评论上构建索引。