ThinkingSphinx: facetted search for ids only

gistfile1.rb

class ThinkingSphinx::FacetIdsSearch < ThinkingSphinx::FacetSearch
  def initialize(*args)
    options = args.extract_options!
    @fast_facet_names = options.delete(:facets) || raise("Missing facet names") 
    @fast_facet_names = [ @fast_facet_names ].flatten.map(&:to_s)

    args.push options
    super *args
  end
    
  def populate
    ThinkingSphinx::Search.bundle_searches(@fast_facet_names) { |sphinx, name|
      sphinx.search *(args + [facet_search_options(name)])
    }.
    each_with_index { |search, index|

      facet_result = search.results[:matches].inject({}) do |hash, match|
        attrs = match[:attributes]
      
        doc, count = attrs["@groupby"], attrs["@count"]
        hash.update doc => count
      end
      
      self[@fast_facet_names[index]] = facet_result 
    }
  end

  def facet_search_options(facet_name)
    limit = max_matches
    options.dup.update :group_function => :attr,
      :limit          => limit,
      :max_matches    => limit,
      :page           => 1,
      :group_by       => facet_name,
      :ids_only       => true
  end
end