Aggregate operation is not returning anything with mongoose schema

The main purpose is to get the total price of the orders array of objects. So I used mongoDB aggregation operation. I used NoSQL booster to check query there I can get the totalPrice but when I use it in the application it just return me an empty array []. Could anybody find which point I am missing

**The example of the object below is shown.

 "userId": 1,
    "username": "john_doe",
    "password": "$2b$12$3fJyHTgM8QgU.q.tlpNVyOf.hJYfhVe7XPGCHm9Wq1RmexUZbUEeu",
    "fullName": {
        "firstName": "John",
        "lastName": "Doe"
    "age": 30,
    "email": "[email protected]",
    "isActive": true,
    "hobbies": [
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "country": "USA"
    "orders": [
            "productName": "Product 1",
            "price": 23.56,
            "quantity": 2
            "productName": "Product 2",
            "price": 23.56,
            "quantity": 5

Below is the function pattern I used

export const GetTotalOrderPriceDB = async (userId: string) => {
 const result = await User.aggregate([
    $match: { userId: userId }, 
    $unwind: "$orders", 
    $group: {
      _id: null, 
      totalPrice: {
      $sum: { $multiply: ["$orders.price", "$orders.quantity"] },
  $project: {
    _id: 0,
    totalPrice: 1,
return result;


  • Well, The issue was very simple I sent "userId" and used that in the first stage of the pipeline.

    Note: userId comes from-

    const userId =

    The userId is a string there thus it can't go next stage of the pipeline. As a result empty string showed.


    const userId = Number( 

    Or const userId = parseInt(

    After changing the userId data type into numbers the aggregation worked.