Mongoose Schema 嵌入文档默认

Question

我正在尝试将一个文档（我猜是一个子文档）嵌入到 Mongoose 架构中。我一直在遵循Mongoose documentation 建议的这种模式。我的架构如下所示。

var CategoriesSchema = new Schema({
    name: { type: String, required: true, default: 'default' }
});

var PostSchmea = new Schema({
    title: { type: String, required: true, default: 'default title' },
    writtenBy: { type: ObjectId, required: true, default: '55878003ebf4b06110ef2ff8' },
    publishedOn: { type: Date, default: Date.now },
    updatedOn: Date,
    published: { type: Boolean, required: true, default: false },
    content: { type: String, required: true, default: 'empty' },
    category: { type: [CategoriesSchema] },
    tags: [String],
    images: [String]
});

如您所见，我将 CategoriesSchema 嵌入到 PostSchema 中。我的问题是如何为 PostSchema 中的类别键设置默认值。我尝试了以下并得到错误“TypeError：无法读取未定义的属性'$__'”：

var PostSchmea = new Schema({
    title: { type: String, required: true, default: 'default title' },
    writtenBy: { type: ObjectId, required: true, default: '55878003ebf4b06110ef2ff8' },
    publishedOn: { type: Date, default: Date.now },
    updatedOn: Date,
    published: { type: Boolean, required: true, default: false },
    content: { type: String, required: true, default: 'empty' },
    category: { type: [CategoriesSchema], default: [CategoriesSchema] },
    tags: [String],
    images: [String]
});

我还尝试了以下方法，得到了错误“SyntaxError: Unexpected token”：

var PostSchmea = new Schema({
    title: { type: String, required: true, default: 'default title' },
    writtenBy: { type: ObjectId, required: true, default: '55878003ebf4b06110ef2ff8' },
    publishedOn: { type: Date, default: Date.now },
    updatedOn: Date,
    published: { type: Boolean, required: true, default: false },
    content: { type: String, required: true, default: 'empty' },
    category: { type: [CategoriesSchema], default: new CategoriesSchema(name: "default") },
    tags: [String],
    images: [String]
});

任何建议或文档将不胜感激。

谢谢，

Answer 1

我相信问题可能在于您的依赖声明。我使用你的代码来声明猫鼬模式，它工作正常，但是你没有包含你的依赖项或你的创建方法，所以让我向你展示我是如何创建记录的，希望对你有所帮助。您还可以参考此 Stack Overflow 答案以获取 ObjectId 的依赖声明：How to set ObjectId as a data type in mongoose

这是我的代码：

//contents of stackoverflow.js
var mongoose = require('mongoose'),
Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;

var CategoriesSchema = new Schema({
    name: { type: String, required: true, default: 'default' }
});


var PostSchmea = new Schema({
   title: { type: String, required: true, default: 'default title' },
   writtenBy: { type: ObjectId, required: true, default:     '55878003ebf4b06110ef2ff8' },
   publishedOn: { type: Date, default: Date.now },
   updatedOn: Date,
   published: { type: Boolean, required: true, default: false },
   content: { type: String, required: true, default: 'empty' },
   category: { type: [CategoriesSchema], default: [CategoriesSchema] },
   tags: [String],
   images: [String]
});

mongoose.model('Post', PostSchmea);
mongoose.model('Categories',CategoriesSchema);

然后我在 server.js 文件中声明了模式和模型以运行代码并创建记录：

//contents of my server.js file (or wherever you put your controllers)    
var stack = require('./app/models/stackoverflow'),
post = mongoose.model('Post');

var v = new post({
  //Define your values here
});

v.save(function(err,docs) {
if (err) {
   console.log(err)

} else {
  console.log(docs)
}
});

这成功创建了具有所有已定义默认值的记录。希望对您有所帮助。