[Typescript] Schema ref property type declaration issue

[Jule-]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

6.6.0

Node.js version

18.15.0

MongoDB server version

5.0.11

Typescript version (if applicable)

5.1.6

Description

There is an issue when defining cross-database ref in a Schema where the Model has TVirtuals type provided.

error TS2322: Type '{ type: typeof Schema.Types.ObjectId; ref: ModelA; }' is not assignable to type 'SchemaDefinitionProperty<ObjectId> | undefined'.
  Types of property 'ref' are incompatible.
    Type 'ModelA' is not assignable to type 'string | Model<any, {}, {}, {}, any> | ((this: any, doc: any) => string | Model<any, {}, {}, {}, any>) | undefined'.
      Type 'Model<IModelA, object, object, IModelAVirtuals, any>' is not assignable to type 'Model<any, {}, {}, {}, any>'.
        Property 'virtualProperty' is missing in type '{}' but required in type 'IModelAVirtuals'.

Steps to Reproduce

// repro.ts
import { model, Model, Schema, Types } from "mongoose";

interface IModelA {
  name: string;
}

interface IModelAVirtuals {
  readonly virtualProperty: string;
}

type ModelA = Model<IModelA, object, object, IModelAVirtuals>;

const modelASchema = new Schema<IModelA, ModelA, object, object, IModelAVirtuals>({
  name: String,
});

modelASchema.virtual("virtualProperty").get(function () {
  return "Virtual!";
});

const A = model<IModelA, ModelA>("ModelA", modelASchema);

interface IModelB {
  a: Types.ObjectId;
}

const modelBSchema = new Schema<IModelB>({
  // Here we use the Model instance for cross-database population
  // https://mongoosejs.com/docs/populate.html#cross-db-populate
  a: { type: Schema.Types.ObjectId, ref: A },
});

const B = model<IModelB>("ModelB", modelBSchema);

npx ts-node repro.ts

Expected Behavior

The ref type declaration should allow virtuals to be present in the Model type.

I think modifying these 2 lines should be enough:

mongoose/types/schematypes.d.ts

Line 88 in 255493b

ref?: string | Model<any> | ((this: any, doc: any) => string | Model<any>);

mongoose/types/schematypes.d.ts

Line 251 in 255493b

ref(ref: string | boolean | Model<any>): this;

Not sure if this type could be inferred somewhere or if it should only be Model<any, any, any, any>.

[IslandRhythms]

This is not occuring on mongoose 7.4.1 so bug is on the described version only

[Jule-]

@IslandRhythms oh yes you are right! So ignore my comments about a potential fix then, it should exist a better solution.

[vkarpov15]

This was fixed in 6.9.3, likely with #13066. Upgrade to >= 6.9.3.