problem with solr joins

product.rb

# Notes:
# a product has_many variants
# conf is just a configuration object that holds a bunch of stuff.  in this case, we're interested in the values
#   for option_facets, which are the values we want to be able to facet on.

  searchable do
    
    if conf.option_facets.present?
      conf.option_facets.each do |option_facet|
        join(option_facet, :type => :integer, :join_string => "from=product_id to=id")
      end
    end
      
  end
  
  # And then my search looks like this:
  
  Product.search do
    with(:frame_design, 195)
  end

variant.rb

# for each entry in option_facets, we want to store the IDs that correspond to that item
# so for the entry :frame_design, we want to store the IDs for the option_values related to "Frame Design" (e.g., standard, wide, etc)

  searchable do
    if conf.option_facets.present?
      conf.option_facets.each do |option_facet|
        option_type_name = option_facet.to_s.titleize
        integer option_facet, :multiple => true, :references => OptionValue do
          option_value_ids_for_types([option_type_name])
        end
      end
    end

    integer :product_id
  end
  
  # finds all the option_values that match the names in "type_array"
  # returns an array of the IDs for those option_values
  def option_value_ids_for_types(type_array)
    return [] if type_array.nil? || type_array.empty?

    matching_option_values = option_values.select { |ov| type_array.include?(ov.option_type.name) }
    matching_option_values.map(&:id).flatten
  end