Dynamic virtual populate not working on subdocument with separate schema

[Hybrid-Force]

Prerequisites

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

Mongoose version

6.5.4

Node.js version

16.15.0

MongoDB server version

4.2.1

Description

Seems to be related to #8277 and #8742

When using dynamic ref on child schema { ref: (doc) => doc.refType }, the passed in doc is the parent document, not the subdocument, causing dynamic ref path not correctly returned.

I tried both virtuals option in schema constructor options and schema virtual() method, tried both ref and refPath in virtual options, none works.

Steps to Reproduce

import mongoose from 'mongoose';
import { expect } from 'chai';

const nestedSchema = new mongoose.Schema({
    targetType: String,
    targetId: mongoose.Schema.Types.ObjectId,
}, {
    virtuals: {
        target: {
            options: {
                ref: (doc: any) => {
                    // doc should be the sub document
                    // but instead, it is the parent document
                    console.debug(doc);
                    return doc.targetType;
                },
                localField: 'targetId',
                foreignField: '_id',
                justOne: true,
            }
        }
    }
});

const parentSchema = new mongoose.Schema({
    nested: {
        type: nestedSchema
    },
});

const NestedDynamicVirtualPopulateTest = mongoose.model('NestedDynamicVirtualPopulateTest', parentSchema);

await NestedDynamicVirtualPopulateTest.collection.drop();
const target = new NestedDynamicVirtualPopulateTest({});
await target.save();

const parent = new NestedDynamicVirtualPopulateTest({
    nested: {
        targetType: (target.constructor as typeof NestedDynamicVirtualPopulateTest).modelName,
        targetId: target._id,
    }
});
await parent.save();
await parent.populate('nested.target');
// @ts-ignore
expect(parent.nested.target).to.exist;

Expected Behavior

Since the virtual is defined on the child schema, the dynamic ref path should be relative to the subdocument, not the parent document.

[IslandRhythms]

12363.ts:49:29 - error TS2551: Property 'target' does not exist on type '{ targetType?: {}; targetId?: { toString: any; _bsontype?: { toString: {}; _bsontype?: ObjectId; inspect?: {}; equals?: {}; _id?: ...; id?: { [x: number]: unknown; [toStringTag]?: unknown; [iterator]?: {}; toString: {}; ... 100 more ...; byteOffset?: unknown; }; toHexString?: {}; toJSON?: {}; generationTime?: unknow...'. Did you mean 'targetId'?

49   console.log(parent.nested.target);
                               ~~~~~~

node_modules/mongoose/types/query.d.ts:619:29 - error TS2304: Cannot find name 'this'.

619     toConstructor(): typeof this;
                                ~~~~


Found 2 errors.

import mongoose from 'mongoose';

const nestedSchema = new mongoose.Schema({
    targetType: String,
    targetId: mongoose.Schema.Types.ObjectId,
}, {
    virtuals: {
        target: {
            options: {
                ref: (doc: any) => {
                    // doc should be the sub document
                    // but instead, it is the parent document
                    console.debug(doc);
                    return doc.targetType;
                },
                localField: 'targetId',
                foreignField: '_id',
                justOne: true,
            }
        }
    }
});

const parentSchema = new mongoose.Schema({
    nested: {
        type: nestedSchema
    },
});

const NestedDynamicVirtualPopulateTest = mongoose.model('NestedDynamicVirtualPopulateTest', parentSchema);
async function run() {
  await mongoose.connect('mongodb://localhost:27017');
  await mongoose.connection.dropDatabase();
  const target = new NestedDynamicVirtualPopulateTest({});
  await target.save();

  const parent = new NestedDynamicVirtualPopulateTest({
      nested: {
          targetType: (target.constructor as typeof NestedDynamicVirtualPopulateTest).modelName,
          targetId: target._id,
      }
  });
  await parent.save();
  await parent.populate('nested.target');
  console.log(parent);
  console.log('=============');
  console.log(parent.nested);
  console.log('=================');
  console.log(parent.nested.target);
  console.log('======================')
}

run();

[Hybrid-Force]

Hi @IslandRhythms, the code snippet in my initial comment was not properly typed, because I thought the type definition does not do much help demonstrating the issue and will make the snippet unnecessarily long. So I just put @ts-ignore before the parent.nested.target part to avoid typing errors :)

[Hybrid-Force]

Hi @IslandRhythms, I think the "typescript" label on this issue is not appropriate. The typing error in your comment is not related to this issue. And this issue is not related to typescript.