[Types] How to set the model type of discriminator?

[lutherman]

Hi,

I tried to set Model type for discriminator, but got the type error.

Codes:

import { Model, model, Schema } from 'mongoose';

const options = { discriminatorKey: 'kind' };
interface IEvent {
  time: Date;
  kind: string;
}

const eventSchema = new Schema<IEvent, Model<IEvent>>({ time: Date }, options);
const Event = model<IEvent, Model<IEvent>>('Event', eventSchema);

interface IClickedLinkEvent extends IEvent {
  url: string;
}

// ClickedLinkEvent is a special type of Event that has
// a URL.
const ClickedLinkEvent = Event.discriminator<
  IClickedLinkEvent, // <-- error here
  Model<IClickedLinkEvent>
>('ClickedLink', new Schema({ url: String }, options));

And the error message:

Type 'IClickedLinkEvent' does not satisfy the constraint 'Document<any, any, any>'.
  Type 'IClickedLinkEvent' is missing the following properties from type 'Document<any, any, any>': $getAllSubdocs, $ignore, $isDefault, $isDeleted, and 48 more.ts(2344)

If my syntax is not correct, would you mind telling me the correct answer?

---

nodejs: 12.19.0
mongodb: 4.2.7
mongoose: 5.13.2

[IslandRhythms]

import * as mongoose from 'mongoose';

const options = { discriminatorKey: 'kind' };
interface IEvent extends mongoose.Document{
  time: Date;
  kind: string;
}

const eventSchema = new mongoose.Schema<IEvent, mongoose.Model<IEvent>>({ time: Date }, options);
const Event = mongoose.model<IEvent, mongoose.Model<IEvent>>('Event', eventSchema);

interface IClickedLinkEvent extends IEvent {
  url: string;
}

const ClickedLinkEvent = Event.discriminator<
  IClickedLinkEvent,
  mongoose.Model<IClickedLinkEvent>
>('ClickedLink', new mongoose.Schema({ url: String }, options));

[lutherman]

Do you mean the interface must extend mongoose.Document?

But mongoose official document (link) recommends not extend:
... This approach works, but we recommend your document interface not extend Document. Using extends Document makes it difficult for Mongoose to infer which properties are present on query filters, lean documents, and other cases. ...

Therefore, i changed all interfaces back into not extend. It took me several days.

Which one should i follow?

[vkarpov15]

@lutherman you're correct, we recommend that your document interface doesn't extends Document. We'll look into this, sorry for the inconvenience.

[lutherman]

@vkarpov15 It’s fine. Thank you for following up.