MongoDB - 猫鼬：如何查询这个？ “填充（）”不起作用。它显示“空”

Question

我有一个页面模式，页面模式有两个对象属性

createdBy

和

approvedBy

.

当我用

.populate("approvedBy").populate("createdBy");

然后显示

"approvedBy": null , "createdBy": null

,

当我不使用

populate()

时，只需使用

find()

然后显示

ObjectId

。但我需要所有嵌套对象，比如使用

populate().

页面架构：

const mongoose = require("mongoose");

const PageSchema = new mongoose.Schema({
  title: {
    type: String,
    require: true,
  },
  description: {
    type: String,
    require: true,
  },
  url: {
    type: String,
  },
  logoURL: {
    type: String,
  },
  backgroundImageURL: {
    type: String,
  },
  button: {
    title: {
      type: String,
      require: true,
    },
    url: {
      type: String,
    },
    color: {
      type: String,
    },
  },
  createdBy: {
    type: mongoose.Types.ObjectId,
    ref: "User",
    require: true,
  },
  approvedBy: {
    type: mongoose.Types.ObjectId,
    ref: "User",
    require: true,
  },
  approve: {
    type: Boolean,
    default: false,
  },
  approveDate: {
    type: Date,
  },
  archive: {
    type: Boolean,
    default: false,
  },
  archiveDate: {
    type: Date,
  },
  createdAt: {
    type: Date,
    default: Date.now,
  },
  updatedAt: {
    type: Date,
  },
});

module.exports = mongoose.model("Page", PageSchema);

通过使用

find()

代码：

const pages = async (req, res, next) => {
  try {
    const pages = await Page.find({})
      .populate("approvedBy")
      .populate("createdBy");
    if (pages === null || pages.length == 0) {
      throw createError(404, "NO DATA FOUND");
    }
    return res.status(200).json({ success: 1, pages });
  } catch (error) {
    return next(createError(error));
  }
};

通过使用

find()

输出：

{
    "success": 1,
    "pages": [
        {
            "button": {
                "title": "Play Now",
                "url": "btnURL",
                "color": "#ff6767"
            },
            "_id": "6425a0d069c436a4f056ba26",
            "title": "Dengen NFT 2",
            "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
            "url": "imgURL",
            "logoURL": "logoURL",
            "backgroundImageURL": "bgURL",
            "createdBy": "64231bf9f21deb779a148c64",
            "approve": false,
            "archive": false,
            "createdAt": "2023-03-30T14:46:40.312Z",
            "__v": 0,
            "approvedBy": "64231b8a6c0398e50a8472d1"
        }
    ]
}

使用

.populate("approvedBy").populate("createdBy")

代码：

const pages = async (req, res, next) => {
  try {
    const pages = await Page.find({}).populate("approvedBy", "createdBy");
    if (pages === null || pages.length == 0) {
      throw createError(404, "NO DATA FOUND");
    }
    return res.status(200).json({ success: 1, pages });
  } catch (error) {
    return next(createError(error));
  }
};

通过使用

.populate("approvedBy").populate("createdBy")

输出：

"approvedBy": null , "createdBy": null

,

{
    "success": 1,
    "pages": [
        {
            "button": {
                "title": "Play Now",
                "url": "btnURL",
                "color": "#ff6767"
            },
            "_id": "6425a0d069c436a4f056ba26",
            "title": "Dengen NFT 2",
            "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
            "url": "imgURL",
            "logoURL": "logoURL",
            "backgroundImageURL": "bgURL",
            "createdBy": null,
            "approve": false,
            "archive": false,
            "createdAt": "2023-03-30T14:46:40.312Z",
            "__v": 0,
            "approvedBy": null
        }
    ]
}

Answer 1

你说你在用：

.populate("approvedBy").populate("createdBy")

但是你已经发布了这个：

.populate("approvedBy", "createdBy")

行不通。

这段代码有效，也许你可以从中拿走一些东西：

import mongoose from "mongoose"

const UserSchema = new mongoose.Schema({
    name: String
})

const PageSchema = new mongoose.Schema({
    createdBy: {
        type: mongoose.Types.ObjectId,
        ref: "User",
        require: true,
    },
    approvedBy: {
        type: mongoose.Types.ObjectId,
        ref: "User",
        require: true,
    },
});

const Page = mongoose.model("Page", PageSchema);
const User = mongoose.model("User", UserSchema);

const run = async () => {
    await mongoose.connect('mongodb://127.0.0.1:27017/75890536');
    const { _id } = await User.create({ name: "username" })

    await Page.create(
        {
            createdBy: _id,
            approvedBy: _id
        })

    const page = await Page.find().populate("createdBy").populate("approvedBy")
    console.log(page)

    await mongoose.disconnect()
}
run()

输出：

[
  {
    _id: new ObjectId("6425c5a767056db481c1f77f"),
    createdBy: {
      _id: new ObjectId("6425c5a767056db481c1f77d"),
      name: 'username',
      __v: 0
    },
    approvedBy: {
      _id: new ObjectId("6425c5a767056db481c1f77d"),
      name: 'username',
      __v: 0
    },
    __v: 0
  }
]

节点：v18.12.1 蒙戈 v6.0.1