custom_searcher.rb

class CustomSearch < Spree::Core::Search::Base

  protected
  def add_search_scopes(base_scope)
    statement = nil
    search.each do |property_name, property_values|
      property = Spree::Property.find_by_name(property_name.gsub("_any", ""))
      next unless property

      substatement = product_property[:property_id].eq(property.id).and(product_property[:value].eq(property_values.first))
      property_values[1..-1].each do |pv|
        substatement = substatement.or product_property[:value].eq(pv)
      end
      tail = product[:id].in(Spree::ProductProperty.select(:product_id).where(substatement).map(&:product_id))
      statement = statement.nil? ? tail : statement.and(tail)
    end if search
    statement ? base_scope.where(statement) : base_scope
  end

  def prepare(params)
    super
    @properties[:product] = Spree::Product.arel_table
    @properties[:product_property] = Spree::ProductProperty.arel_table
  end
end