class Search
  attr_reader :klass, :query, :keywords, :user

  def initialize(klass, query, user = nil)
    @klass = klass
    @query = query
    @keywords = query.gsub(/[^0-9a-z ]/i, "").split(" ").map(&:downcase)
    @user = user
  end

  def results
    @results ||= begin
      save_event

      all_matches = (matches_by_tag + matches_by_title).uniq
      all_matches.sort_by { |item| relevancy_score(item) }.reverse
    end
  end

  private

  def matches_by_tag
    tags = ActsAsTaggableOn::Tag.joins(:taggings)
                                .where(name: keywords, taggings: { taggable_type: klass.name })
                                .uniq

    tags.flat_map(&:taggings)
        .select { |t| t.taggable_type == klass.to_s }
        .map(&:taggable)
  end

  def matches_by_title
    klass.where("title ~* ?", keywords.join("|"))
  end

  def relevancy_score(item)
    tag_score = (item.tag_list & keywords).size
    title_score = keywords.select { |kw| item.title.downcase.include?(kw) }.size * 2

    tag_score + title_score
  end

  def save_event
    LoggedEvent.create(actor: user, details: { query: query, keywords: keywords })
  end
end
class Search
  attr_reader :klass, :query, :keywords, :user

  def initialize(klass, query, user = nil)
    @klass = klass
    @query = query
    @keywords = query.gsub(/[^0-9a-z ]/i, "").split(" ").map(&:downcase)
    @user = user
  end

  def results
    @results ||= begin
      save_event

      all_matches = (matches_by_tag + matches_by_title).uniq
      all_matches.sort_by { |item| relevancy_score(item) }.reverse
    end
  end

  private

  def matches_by_tag
    tags = ActsAsTaggableOn::Tag.joins(:taggings)
                                .where(name: keywords, taggings: { taggable_type: klass })
                                .uniq

    tags.flat_map(&:taggings)
        .select { |t| t.taggable_type == klass.to_s }
        .map(&:taggable)
  end

  def matches_by_title
    klass.where("title ~* ?", keywords.join("|"))
  end

  def relevancy_score(item)
    tag_score = (item.tag_list & keywords).size
    title_score = keywords.select { |kw| item.title.downcase.include?(kw) }.size * 2

    tag_score + title_score
  end

  def save_event
    LoggedEvent.create(actor: user, details: { query: query, keywords: keywords })
  end
end
--- 
+++ 
@@ -21,7 +21,7 @@
 
   def matches_by_tag
     tags = ActsAsTaggableOn::Tag.joins(:taggings)
-                                .where(name: keywords, taggings: { taggable_type: klass })
+                                .where(name: keywords, taggings: { taggable_type: klass.name })
                                 .uniq
 
     tags.flat_map(&:taggings)
Fix Search for Rails 5.
