解决方法
现在,我使用了一种非常简单的方法,它非常有效：只需包含一个数组字段.
#app/models/image.rb
class Image
include Mongoid::Document
include Mongoid::Timestamps
field :message,:type => String
field :tags,:type => Array
def self.images_for tag
Image.any_in(:tags => [tag])
end
end
#routes.rb
match "tag/:tag" => "images#tag"
#/app/controller/images_controller.rb
class ImagesController < ApplicationController
# GET /tag
# GET /tag.xml
def tag
@images = Image.images_for params[:tag]
respond_to do |format|
format.html { render "index" }
format.xml { render :xml => @images }
end
end
end
这有效,但我仍然对Image.any_in map / reduce的性能有点怀疑.我认为可能有一个更好的解决方案,但尚未找到它.