Try to populate in mongoose and it doesn't work (nodejs)

Question

i Make mini cart with Product and user Auth, Evereting work perfect but whan i try to make a route that pickup all the product from the user and view them in specific page and it not work for me. it returns the user but not the product.

UserSchema

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

const UserSchema = new Schema({
  product: {
    type: [mongoose.Schema.Types.ObjectId],
    ref: "product"
  },
  name: {
    type: String,
    required: true
  },
  email: {
    type: String,
    required: true,
    unique: true
  },
  address: {
    type: String,
    required: true
  },
  password: {
    type: String,
    required: true
  },
  data: {
    type: Date,
    default: Date.now
  }
});

module.exports = User = mongoose.model("user", UserSchema);

ProductScheama

const mongoose=require('mongoose');

const ProductSchema = new mongoose.Schema({
    name:{
        type:String,
        required:true,
        unique:true
    },
    description:{
        type:String,
    },
    price:{
        type:Number,
        required:true
    },
    quantity:{
        type:Number,
        required:true
    },
    data:{
        type:Date,
        default:Date.now
    }
})

module.exports=Product=mongoose.model('product',ProductSchema)

I am trying to create a function that gives me the name, price and description of the product and it fails. my router:

router.get("/products/:id", auth, async (req, res) => {
  try {
    let pro = await User.find({ product: req.params.id }).populate("product", [
      "name",
      "price",
      "description"
    ]);
    if (!pro) {
      return res.json({ msg: "This user not have products to show" });
    }
    res.json(pro);
  } catch (err) {
    console.error(err.message);
    res.status(500).send("Server errors");
  }
});

result from Postman:

[
    {
        "product": [],
        "_id": "5d5bfb96963ca600ec412bca",
        "name": "Anonny Annon",
        "email": "Annony@gmail.com",
        "address": "Israel",
        "password": "$2a$10$gESTIaBVifzhRDR2zOKsw.Q79gCT07IK2VnDoyT2oU5htqfBuAj8W",
        "data": "2019-08-20T13:54:30.267Z",
        "__v": 0
    }
]

Answer 1

I think product should be defined this way :

product: [{
    type: mongoose.Schema.Types.ObjectId,
    ref: "product"
}]

instead of type: [mongoose.Schema.Types.ObjectId]

Solution found here