Populated field type

[wasya243]

Hello! Please help me. Here is the code.

import { prop, getModelForClass, Ref } from '@typegoose/typegoose';
import mongoose from 'mongoose';

export class Organization {
  @prop({required: true})
  name!: string;

  @prop({
    ref: () => User,
    foreignField: 'organizationId',
    localField: '_id'
  })
  public users: Ref<User>[] = [];
}
export class User {
  @prop({required: true})
  name!: string;

  @prop({
    ref: () => Organization, 
    required: true,
    foreignField: '_id',
    localField: 'organizationId',
    justOne: true
  })
  private organization!: Ref<Organization>;

  @prop({ required: true })
  public organizationId!: string;

}

const OrganizationModel = getModelForClass(Organization, {
  schemaOptions: {
    toJSON: { virtuals: true },
    toObject: { virtuals: true }
  }
});

const UserModel = getModelForClass(User, {
  schemaOptions: {
    toJSON: { virtuals: true },
    toObject: { virtuals: true }
  }
});
async function main() {
  try {
    await mongoose.connect('mongodb://localhost:27017/', {dbName: 'migration-to-typegoose'});

    const organization = await OrganizationModel.create({
      name: 'Acme Inc.'
    });

    const users = await Promise.all([
      UserModel.create({
        name: 'Vasyl',
        organizationId: organization._id.toString()
      }),
      UserModel.create({
        name: 'Misha',
        organizationId: organization._id.toString()
      })
    ]);

    const user = await UserModel.findOne().populate('organization');

    // here is TS error that name does not exist on organization
    console.log(user.organization.name)

    // possible solutions

    // 1) const user = await UserModel.findOne().populate<{organization: Organization}>('organization');
    // 2) same as above but define interface 
    // 3) typecasting to any
    // 5) if isDocument

    process.exit(0);
  } catch (err) {
    console.error(err);
    process.exit(1);
  }
}

main();

There are 2 entities: organization and user. Organization has many users. I do populate on user (populating organization). After that I try acccessing .name on populated organization field. I get TS error.

Basically my question is there any other way to access fields on populated field without interfaces, typecasts, isDocument?

[hasezoey]

I get TS error.

i think the error is missing

Basically my question is there any other way to access fields on populated field without interfaces, typecasts, isDocument?

no, you need to use one of the following:

• isDocument by either early-returning or only doing processing in the if block
• typecasing with ! (non-null assertion operator)
• use some assertion (like assert.ok(isDocument(doc.path)), normal nodejs assert wont work because it does not have proper typing, see typegoose's assertion for example)
• use some type-casting via the NonNullable utility type (basically the same as ! just longer)
• use manual casting of the type (not recommended) via const yourPath = doc.path as YourClass (not recommended)

[wasya243]

Thanks for your answer! I guess the error is not missing -> I wrote "TS error that name does not exist on organization" in the code example. Regarding typecasting with "!" operator or NonNullable utility type -> it's not going to work or I got you wrong. If I put "!" like this user!.organization!.name I still get the following error Property 'name' does not exist on type 'Ref'. Property 'name' does not exist on type 'ObjectId'. So problem is not about possible undefined/null values, but about types.

[hasezoey]

i dont know why i wrote this, but yes, ! and NonNullable do not help in this way, sorry about that.

so to your original question, your only options are:

• use isDocument via a early-return (via if () return or assertion) or only operate in that if-block
• use manual type-casting

[wasya243]

Yeap, cool!

[olawalejuwonm]

#813 (comment)

[olawalejuwonm]

Is this possible without casting, can typegoose automatically set the type when I do .populate for the field being populated?

[hasezoey]

no typegoose does not do this automatically, to do this automatically typegoose would require to overwrite the mongoose populate type (which typegoose avoids doing)

but mongoose provides some way to overwrite the path via a generic: .populate<{ field: PopulatedType }>(selector) (see mongoose documentation)

also in addition populate modifies the document in-place, but typescript does not support in-place type changes (to my knowledge) so to to actually make the mongoose way useful, you would have to do doc = doc.populate() (reassigning the value)

[olawalejuwonm]

When I use Ref<User> it should at least give the user type. Or what's even advantage of Ref over using ObjectID?

…

On Tue, Sep 19, 2023, 14:44 hasezoey ***@***.***> wrote: no typegoose does not do this automatically, to do this automatically typegoose would require to overwrite the mongoose populate type (which typegoose avoids doing) but mongoose provides *some* way to overwrite the path via a generic: .populate<{ field: PopulatedType }>(selector) (see mongoose documentation <https://mongoosejs.com/docs/typescript/populate.html>) also in addition populate modifies the document in-place, but typescript does not support in-place type changes (to my knowledge) so to to actually make the mongoose way useful, you would have to do doc = doc.populate() (reassigning the value) — Reply to this email directly, view it on GitHub <#813 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AMSQ2BHO66RN7JX6CSS62S3X3GOTDANCNFSM6AAAAAAWYYQYYQ> . You are receiving this because you commented.Message ID: ***@***.***>

[hasezoey]

this is basically the question this discussion was originally about, see comment #813 (reply in thread)

TL;DR: Ref is a combination of the ref-type (objectid in most cases) and the class itself, and need to be filtered out after population, because population can fail

[olawalejuwonm]

Ok, how do I filter that out please?

…

On Tue, Sep 19, 2023, 18:22 hasezoey ***@***.***> wrote: this is basically the question this discussion was originally about, see comment #813 (reply in thread) <#813 (reply in thread)> TL;DR: Ref is a combination of the ref-type (objectid in most cases) and the class itself, and need to be filtered out after population, because population can fail — Reply to this email directly, view it on GitHub <#813 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AMSQ2BFLHZNNAH3RMZALXNDX3HIFZANCNFSM6AAAAAAWYYQYYQ> . You are receiving this because you commented.Message ID: ***@***.***>

[hasezoey]

see #813 (reply in thread) and Reference other Classes: Population

[olawalejuwonm]

Thanks