Mongoose - 使用判别器划分子文档

Question

如果我有一个 model Attachment，它可以分为 4 种类型：Link、YoutubeVideo、GoogleDriveFile、 和GoogleDriveFolder，我如何使用 Mongoose 区分Attachment这些类型，并允许它们成为另一个模式中的子文档；Post？

我创建了基本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架构中，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。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，也找不到任何解释如何执行此操作的文档。帮助？

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