Rails:渴望加载as_json包含

Question

  render :json => {
    "playlist" => playlist_description,
    "songs" => @playlist.songs.as_json(:include => {:playlist_songs => {:only => [:id, :position]}})
  }

上面的代码导致对数据库的1 + N个查询,一个用于加载每首歌曲的playlist_songs.播放列表预装在@playlist中.

这太慢了,我该如何优化？

Answer 1

我的猜测:你现在还没有急于加载播放列表.您当前正在等待as_json调用 - 之后所有歌曲都已加载 - 然后代码必须迭代每首歌曲然后获取playlist_songs.

我的猜测(这是完全未经测试的,可能包含错误)

@playlist.songs.all(:include => :playlist_songs).as_json(:include => {:playlist_songs => {:only => [:id, :position]}})

AFAICT,这应该首先加载所有歌曲和 playlist_songs ...然后渲染为json.