Search on multiple fields using regexp (mongodb)

# Extend MongoMapper Objects
# Usage :
# -------
# MyModel.search(["title", "text"], "my search", { :flag => nil }, { :limit => 10 })

module MongoMapper
  module Document
    module ClassMethods
      def search(fields, words, conditions = {}, options = {})
        filters = []
        words.split(" ").each do |word|
          ftemp = []
          fields.each {|field| ftemp << "(this.#{field} === null ? false : this.#{field}.match(new RegExp('#{word}','i')))" }
          filters << "(#{ftemp * " || "})"
        end
        filters = filters * " && "

        all({:conditions => { "$where" => filters }.merge(conditions) }.merge(options))
      end
    end
  end
end