猫鼬嵌入的文档/DocumentsArrays ID [英] Mongoose embedded documents / DocumentsArrays id

问题描述

在Mongoose文档中的以下地址: http://mongoosejs.com/docs/embedded-documents.html

In the Mongoose documentation at the following address: http://mongoosejs.com/docs/embedded-documents.html

有一条声明:

DocumentArrays具有特殊的方法ID，可过滤您的嵌入式 文档的_id属性(每个嵌入式文档获取一个):

DocumentArrays have an special method id that filters your embedded documents by their _id property (each embedded document gets one):

请考虑以下代码段:

 post.comments.id(my_id).remove();
  post.save(function (err) {
    // embedded comment with id `my_id` removed!
  });

我已经查看了数据，但嵌入式文档没有 _id ，这似乎已由本帖子确认:

I've looked at the data and there are no _ids for the embedded documents as would appear to be confirmed by this post:

如何返回上一个push()嵌入式文档

我的问题是:

文档是否正确?如果是这样，那么我如何找出"my_id"是什么(在示例中)，以便首先执行'.id(my_id)'?

Is the documentation correct? If so then how do I find out what 'my_id' is (in the example) to do a '.id(my_id)' in the first place?

如果文档不正确，可以安全地将索引用作文档数组中的ID，或者我应该手动生成唯一的ID(根据所提到的内容).

If the documentation is incorrect is it safe to use the index as an id within the document array or should I generate a unique Id manually (as per the mentioned post).

推荐答案

不是对像这样的json对象(猫鼬文档建议的方式)进行push():

Instead of doing push() with a json object like this (the way the mongoose docs suggest):

// create a comment
post.comments.push({ title: 'My comment' });

您应该创建嵌入式对象的实际实例，并创建push().然后，您可以直接从中获取_id字段，因为猫鼬在实例化对象时对其进行设置.这是一个完整的示例:

You should create an actual instance of your embedded object and push() that instead. Then you can grab the _id field from it directly, because mongoose sets it when the object is instantiated. Here's a full example:

var mongoose = require('mongoose')
var Schema = mongoose.Schema
var ObjectId = Schema.ObjectId

mongoose.connect('mongodb://localhost/testjs');

var Comment = new Schema({
    title     : String
  , body      : String
  , date      : Date
});

var BlogPost = new Schema({
    author    : ObjectId
  , title     : String
  , body      : String
  , date      : Date
  , comments  : [Comment]
  , meta      : {
        votes : Number
      , favs  : Number
    }
});

mongoose.model('Comment', Comment);
mongoose.model('BlogPost', BlogPost);

var BlogPost = mongoose.model('BlogPost');
var CommentModel = mongoose.model('Comment')


var post = new BlogPost();

// create a comment
var mycomment = new CommentModel();
mycomment.title = "blah"
console.log(mycomment._id) // <<<< This is what you're looking for

post.comments.push(mycomment);

post.save(function (err) {
  if (!err) console.log('Success!');
})

这篇关于猫鼬嵌入的文档/DocumentsArrays ID的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！