Mongodb数据抽取

Question

我在找一些关于mongoDB的帮助。我正在和mongodb和mongoose一起做一个音乐节点项目。我有3个mongoose模式：

​

// define the schema for our user model
var userSchema = mongoose.Schema({
    _id: Schema.Types.ObjectId,
    local: {
        username: String,
        password: String
    },
    spotify: {
        id: String,
        token: String,
        username: String,
        profileUrl: String,
        email: String
    },
    deezer: {
        id: String,
        token: String,
        username: String,
        profileUrl: String,
        email: String
    },
    youtube: {
        id: String,
        token: String,
        displayName: String
    }
});

var musicSchema = mongoose.Schema({
  _id: Schema.Types.ObjectId,
  author_id: {
    type: Schema.Types.ObjectId,
    ref: 'User'
  },
  url: String,
  file: String,
  title: String,
  artistName: String,
  deezerId: Number,
  itunesId: Number,
  position: Number,
  duration: Number,
  deezerAlbum: Number,
  discNumber: Number,
  album: String,
  releaseDate: Date,
  nbTracks: Number,
  genreId: Number,
  cover: String,
  genre: String,
  creationDate: {
    type: Date,
    default: Date.now
  }
});

var playlistSchema = mongoose.Schema({
  _id: Schema.Types.ObjectId,
  name: String,
  author_id: {
    type: Schema.Types.ObjectId,
    ref: 'User'
  },
  contributor_id: [{
    type: Schema.Types.ObjectId,
    ref: 'User'
  }],
  tag: [String],
  importedPl: [String],
  musics: [Schema.Types.ObjectId],
  syncImportedPlaylist: {
    type: Boolean,
    default: false
  },
  autoAddSimilarSong: {
    type: Boolean,
    default: false
  },
  creationDate: {
    type: Date,
    default: Date.now
  }
});

​

简单地解释一下，事情是这样的。我有一个用户，音乐和播放列表模式。我想提取一个播放列表，里面有所有的音乐和用户，这样最终的JS对象看起来就像这样：

​

{
  _id: someID
  name: String,
  author: {
    _id: someID
    local: {...},
    spotify: {...},
    deezer: {...},
    youtube: {...}
  },
  contributor: [{
    _id: someID
    local: {...},
    spotify: {...},
    deezer: {...},
    youtube: {...}
  }, {
    _id: someID
    local: {...},
    spotify: {...},
    deezer: {...},
    youtube: {...}
  }],
  musics_ids: [{
  _id: someID
  author: {
    _id: someID
    local: {...},
    spotify: {...},
    deezer: {...},
    youtube: {...}
  },
  url: String,
  file: String,
  title: String,
  ...allTheMusicSchemaInfo...: ...
}],
  ...allThePlaylistSchemaInfo...: ...
}

​

我想用数据本身替换..._id (即用用户数据替换author_id，musics_ids也是如此)。

编辑:在这里回答(thx @matheusds)：https://stackoverflow.com/a/48727050/7841588

Answer 1

要引用其他集合中的文档，可以使用more details here中描述的populate方法。

此方法自动将文档中的路径替换为其他集合中的文档。