猫鼬在所有嵌套对象中添加_id [英] Mongoose adds _id to all nested objects

问题描述

在创建带有嵌套对象(例如对象数组)的文档时，每个对象都具有自己的_id.例如，我的架构如下所示:

When creating a document with nested objects (e.g. an array of objects), each object is given its own _id. For example, my schema looks like this:

mongoose = require "mongoose"

Schema = mongoose.Schema

schema = new Schema
  name:
    type: String
    required: true
    unique: true
    trim: true

  lists: [
    list:
      type: Schema.Types.ObjectId
      required: true
      ref: "List"
    allocations: [
      allocation:
        type: Number
        required: true
    ]
  ]

  createdAt:
    type: Date
    default: Date.now

  updatedAt:
    type: Date

# Ensure virtual fields are serialised.
schema.set "toJSON",
  virtuals: true

exports = module.exports = mongoose.model "Portfolio", schema

在最终创建文档时，lists数组中的每个对象都被赋予_id，而lists.allocations数组中的每个allocation对象也被赋予_id.这似乎有些矫kill过正，并且使文档blo肿，但是MongoDB(或Mongoose)需要文档包含此附加信息是有原因的吗?如果没有，我想防止它发生，以便唯一的_id位于根文档上.

Every object in the lists array is given an _id, as is every allocation object in the lists.allocations array, when documents are eventually created. This seems like overkill and bloats the document, but is there a reason MongoDB (or Mongoose) needs the document to contain this additional information? If not, I'd like to prevent it from happening so that the only _id is on the root document.

此外，猫鼬会自动为_id创建一个虚拟id，这是我需要的，因为我的客户端代码需要一个字段id.这就是为什么我要用JSON返回虚拟机的原因.但是，由于整个文档中都有_id个字段，而不仅仅是在根目录中，因此此虚拟副本重复了 all 个.如果无法阻止其他_id字段，如何获得仅应用于根文档_id的虚拟?或者，如果有更好的方法来做我要尝试做的事，那会是什么?

Furthermore, Mongoose automatically creates a virtual id for _id, which I need because my client code expects a field id. This is why I'm having virtuals returned with JSON. However, because there are _id fields all throughout the document, not just at the root, this virtual duplicates all of them. If there is no way to prevent the additional _id fields, how can I get a virtual to only apply only to the root document _id? Or if there is a better way to do what I'm trying to do with it, what would it be?

推荐答案

我已经找到了一种使用相同技术解决这两个问题的方法:通过为每种嵌套对象类型使用显式架构并设置其_id和 false的选项.看起来，当嵌套定义内联"的对象时，Mongoose为幕后的每个对象创建架构.由于架构的默认值为_id: true和id: true，因此它们将获得_id并具有虚拟的id.但是通过使用显式架构覆盖它，我可以控制_id的创建.更多代码，但是我得到了我想要的:

I have figured out a way to solve both issues with the same technique: by using explicit schemas for each nested object type and setting their _id and id options to false. It seems that when nesting objects that you define "inline", Mongoose creates schemas for each of those objects behind the scenes. Since the default for a schema is _id: true and id: true, they will get an _id as well as have a virtual id. But by overriding this with an explicit schema, I can control the _id creation. More code, but I get what I want:

mongoose = require "mongoose"

Schema = mongoose.Schema

AllocationSchema = new Schema
  allocation:
    type: Number
    required: true
,
  _id: false
   id: false

mongoose.model "Allocation", AllocationSchema

ListsSchema = new Schema
  list:
    type: Schema.Types.ObjectId
    required: true
    ref: "List"
  allocations: [AllocationSchema]
,
  _id: false
   id: false

mongoose.model "Lists", ListsSchema

PortfolioSchema = new Schema
  name:
    type: String
    required: true
    unique: true
    trim: true

  lists: [ListsSchema]

  createdAt:
    type: Date
    default: Date.now

  updatedAt:
    type: Date

这篇关于猫鼬在所有嵌套对象中添加_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！