ruby-object-mapper

问题 Given: create_table(:foos) do primary_key(:id) String(:name) end create_table(:bars) do primary_key(:id) String(:name) end create_table(:foos_bars) do primary_key(:id) foreign_key(:foo_id, :foos) foreign_key(:bar_id, :bars) String(:name) end class Foos < ROM::Relation[:sql] dataset :foos def with_bars(id) prefix('foos').qualified.select( :foos__id, :foos__name ).select_append( :bars__id, :bars__name ).left_join( :foos_bars, foos_bars__bars_id: :foos__id ).left_join( :bars, bars__id: :foos