Nestjs Mongoose, How to delete array member by its _id? - mongodb

Question

The schema is like this. it's a shopping cart with items:
export interface Cart extends mongoose.Document {
userId: string;
total: number;
count: number;
status: string;
items: [
{
itemId: string;
itemName: string;
count: number;
price: number;
itemTotal: number;
},
];
}
if you look at the mondodb data, there is an _id to each of the members in items array.
I have this _id, and i want to remove an item by that _id.
The problem is, it's typescript, and _id is not part of the schema.
Here is the code i use to delete an item:
const cart = await this.cartModel.findOneAndUpdate(
{ _id: dto.cartId },
{ $pull: { items: { _id: '1234567890' } } },
{ new: true },
);
Which means, in that specific cart, find the item with _id equals to 1234567890, and delete it.
BUT the _id has red squiggly, as it is not part of my schema.
How can I solve this?

Answer 1

It shoulds be id not _id. Because _id is an object. But our query cannot send object to params. So, it should be a hexString.
You can change your entity _id to id by:
#ObjectIdColumn()
#Transform(id => id.toString())
id: string;
So that, you can use id as hexString anywhere. Hope it helps

Answer 2

For lack of better solution, i have bypassed this issue by adding a text field called timeStamp. when an item is added to the cart, i push the current time (in ms) to that field, and that is unique enough to distinguish between entries in a shopping cart. In case you wonder, itemId is not good enough, as people can have the same item in 2 or more lines, with different details. I have added of course the new field to my schema, so typescript is not complaining ;)