Using ObjectId Type

Using the type ObjectId can be done by defining it as follows:

import mongoose from 'mongoose';
import { prop } from '@typegoose/typegoose';

class FooModel {
  @prop()
  userId: mongoose.Types.ObjectId;
}

You need to refer to the full length type since defining it as type ObjectId = mongoose.Types.ObjectId and referencing that will lead to it being an Object at compile time, meaning Typegoose will translate the property type to Mixed.

In order to query this model later you should use the type mongoose.Types.ObjectId.

const FooModel = getModelForClass(FooModel);
FooModel.findOne({ userId: new mongoose.Types.ObjectId('5e997f95d6a35f3a0def3339') });