discriminatorKey on insert?

[seanlee10]

var ItemSchema = new Schema({
    id: Number,
    created: { type: Date, default: Date.now }
}, { collection : 'items', discriminatorKey : '_type' });

This is my parent schema, and it is extended by 2 child schemas Car and Truck.

Car.collection.insert([{'photo':'/civic.jpg'},{'photo':'/accord.jpg'}], function (err) {})
Truck.collection.insert([{'photo':'/sierra.jpg'},{'photo':'/titan.jpg'}], function (err) {})

But unlike your example, I used insert as I wanted create records in bulk.

and after the insertion, I don't see '_type' field populated in the items collection.

So I was wondering if the 'discriminatorKey' only works for save() and not for insert().

Could you share some insight on this matter? Thanks!