I have an issue with my request and response. I am handling issues when the customer wants to add more than one of the same item with a different size.
What I first do is check if the Id exist by doing a count on and a if statement. If exist I create a a new object id using ({“_id”: ObjectId()}) with no parameters. It all works as expected same object insert but with new id. What I do next is send a different response and it shows the response with the different Id, but when I try to do an update on the response Id it updates the id of the request.

I understand that the response goes back to calling function, but my question is how do I get it to look at the new response Id. I’m stuck, I know I’m missing something. I would be great if some one could point me in the right direction. I would really appreciate your help.

code snippet below:

router.post('/getProducts/addtocart:_id',   async(req, res)=> {

   var _id = req.params._id; 

 let productCart= await Products.findById({_id});

 ......mongosse connection

       if(err){
    console.log(err)
  }else{
    console.log("Count:", count)
  }

  if(count>0){
      console.log("Product exist");

      productCart._id = ({"_id" : ObjectId()});

         console.log("what is new productCart ID", productCart._id)
         console.log("now whats in cart with new Id", productCart)

  db.collection('carts').insertOne(productCart, function(err, result){ 
                      
        if(err) {  

          console.log(err)
        }

        else{
       
          console.log("What is ID for res", productCart._id)
          res.send((productCart))
        
        
        }
   
      }

      
    )

}
}else{

 .........

    Response with new _id

calling function:

 handleAddToCart(){

  this.Valuesize;


  this.cartService.addProductToCart(this.productItem, 
 this.productItem._id, this.Valuesize).subscribe(()=> {

    this.form.reset();

   })


  this.handleUpdateCart()//call to update cart


 }


 handleUpdateCart(){

   this.cartService.UpdateCart(this.productItem, this.productItem._id, 
   this.size).subscribe(()=> {
})  


}

As can see from the screen shot I do get the response with the new Id.
I’m not sure if I should add an Id. Any help would be grateful. I’m close but not on the money.