realty_objects_controller.rb

  def check_location_type
    if types = params['search2'].try{|x| x['location_types']}
      unless (valid_types = types.keys.select{|k| k.to_i >= 1 && k.to_i <= 5}).empty?
        models = { 2 => Region, 3 => City, 4 => MunRegion, 5 => Road }

        valid_types.each do |id|
          ids = types[id].split(',').map(&:to_i)

          if id == '1'
            @realty_objects = @realty_objects.joins(:location => :metro_stations)
              .where('locations_metro_stations.metro_station_id in (?)', ids)
          else
            model = models[id.to_i]
            field = model.table_name[0..-2] + '_id'
            locations_ids = Location.where(field => ids).map{|loc| loc.id}
            @realty_objects = @realty_objects.where id: locations_ids
          end
        end
      end
    end
  end