Javascript 如何在mongoose中链接两个模型

有两个模型，ProductModel和分类模型.

目的:在创建一个产品(ProductModel)时，分别为其分配一个类别，类别集合中应该填充一个产品数组，但它们之间的连接不起作用.当创建一个产品(ProductModel)时，我通过json输出响应，它包含了除了category字段之外的所有字段，我还需要填写这个字段.

产品型号

import { Schema, model } from 'mongoose'

const ProductModel = new Schema({
    productName: { type: String, required: true },
    price: { type: Number, required: true },
    preview: { type: String },
    color: { type: String, required: true },
    specs: {
        images: [{ type: String }],
        memory: { type: Number },
        ram: { type: Number },
        diagonal: { type: String },
    },
    category: {
        name: String,
        type: Schema.Types.ObjectId,
        ref: 'Category',
    },
})

export default new model('Product', ProductModel)

分类模型

import { Schema, model } from 'mongoose'

const 分类模型 = new Schema({
    name: {
        type: String,
        required: true,
    },
    products: [
        {
            type: Schema.Types.ObjectId,
            ref: 'Product',
        },
    ],
})

export default new model('Category', 分类模型)

产品创建路由的逻辑

  async post(req, res, next) {
        try {
            // Get fields from client
            let { productName, price, preview, color, specs, category } = req.body

            // Looking for a category transferred from a client
            const productCategory = await 分类模型.find({ name: category })
            console.log(productCategory)

            // Creating product
            const doc = new ProductModel({
                productName,
                price,
                preview,
                color,
                specs,
                category: productCategory._id,
            })

            // Save product
            const product = await doc.save()

            // Returning a response from the server to the client
            return res.json(product)
        } catch (error) {
            console.log(error.message)
        }
    }

以下是我发送到服务器和从服务器接收的内容

Request:
{
    "productName": "Air pods pro",
    "price": 123,
    "preview": "preview",
    "color": "red",
    "specs": {
        "images": ["image1, image2, image3"],
        "memory": 64,
        "ram": 16,
        "diagonal": "diagonal"
    },
    "category": "AirPods"
}

Response:
{
    "productName": "Air pods pro",
    "price": 123,
    "preview": "preview",
    "color": "red",
    "specs": {
        "images": [
            "image1, image2, image3"
        ],
        "memory": 64,
        "ram": 16,
        "diagonal": "diagonal"
    },
    "_id": "6609ad76341da85122e029d0",
    "__v": 0
}

正如您所看到的，响应中没有类别字段，就像在数据库中一样，每个产品都缺少这个字段.Category集合中包含了一系列产品，也没有被填满

我会在下面附上截图

Mongo. Mongo.