Mongoose - 使用判别器划分子文档

Question

如果我有一个模型

Attachment

，它可以分为4种类型：

Link

、

YoutubeVideo

、

GoogleDriveFile

和

GoogleDriveFolder

，我如何使用Mongoose将

Attachment

区分为这些类型，以及允许它们成为另一个模式中的子文档；

Post

？

我创建了基础

Attachment

模型，并使用判别器将其划分为单独的模型：

var AttachmentSchema = new Schema({
    id:     {type: String, required: true},
    title:  {type: String, required: true}
});

var Attachment = mongoose.model('Material', AttachmentSchema);

module.exports = {
    DriveFile:      Attachment.discriminator('GoogleDriveFile', new mongoose.Schema()),
    DriveFolder:    Attachment.discriminator('GoogleDriveFolder', new mongoose.Schema()),
    Link:           Attachment.discriminator('Link', new mongoose.Schema()),
    YoutubeVideo:   Attachment.discriminator('YoutubeVideo', new mongoose.Schema())
};

现在，在

Post

模式中，应该有一系列具有不同类型的附件：

var Attachment = require('./attachment');

var PostSchema = new Schema(
    text:{type: String},
    attachments: [Material] // Could be Material.Link, Material.YoutubeVideo, etc
});

当我这样做时，我收到一条错误消息“未定义类型

Model

at

GoogleDriveFile

。您尝试过嵌套架构吗？您只能使用引用或数组进行嵌套。”

我不知道这个错误意味着什么，而且我找不到任何解释如何执行此操作的文档。帮忙吗？

Answer 1

尝试执行以下操作：

    var AttachmentSchema = new Schema({
    id:     {type: String, required: true},
    title:  {type: String, required: true}
    });

var PostSchema = new Schema({
    text: { type: String },
    attachments: [ AttachmentSchema ] // Could be Material.Link, Material.YoutubeVideo, etc
});

var attachmentArray = PostSchema.path('attachments');

    module.exports = {
    Post: mongoose.model('Post', PostSchema),
    DriveFile:      attachmentArray.discriminator('GoogleDriveFile', new mongoose.Schema({})),
    DriveFolder:    attachmentArray.discriminator('GoogleDriveFolder', new mongoose.Schema({})),
    Link:           attachmentArray.discriminator('Link', new mongoose.Schema({})),
    YoutubeVideo:   attachmentArray.discriminator('YoutubeVideo', new mongoose.Schema({}))
};

关键是不要使用猫鼬模型，使用父文档模式的 schema.path 作为鉴别器的基础。

在此链接上搜索术语 docArray：Mongoose Discriminator 文档

Answer 2

对于其他正在使用NestJS和

nestjs/mongoose

的人，以Scott Gnile的回答为参考，你可以这样做：

主要架构

@Schema()
export class MainClass {
  // some properties here

  @Prop({ type: SubClass })
  sub: SubClass;
}
export const MainClassSchema = SchemaFactory.createForClass(MainClass);

子架构

@Schema({ _id: false, discriminatorKey: 'kind' })
export class SubClass {
  @Prop({ required: true, type: String, enum: Foo })
  kind: string;

  // Timestamp as an example for shared properties
  @Prop({ default: Date.now })
  timestamp: Date;
}


@Schema({ _id: false })
export class SubClassBar {
  kind = Foo.Bar; // Set the discriminator to the correct value

  // Add further props
}
export const SubClassBarSchema = SchemaFactory.createForClass(SubClassBar);

模块内部

@Module({
  imports: [
    { name: MainClass.name, schema: MainClassSchema },
    {
      name: SubClass.name,
      schema: MainClassSchema.path('sub').schema, // notice the .schema
      discriminators: [
        { name: Foo.Bar, schema: SubClassBarSchema },
        // add further kinds here
      ]
    }
  ]
})
export class MainModule { }