build_select

# File activerecord/lib/active_record/relation/query_methods.rb, line 1011
    def build_select(arel, selects)
      if !selects.empty?
        expanded_select = selects.map do |field|
          columns_hash.key?(field.to_s) ? arel_table[field] : field
        end
        arel.project(*expanded_select)
      else
        arel.project(@klass.arel_table[Arel.star])
      end
    end