Superclassing Realm.Object<T>

[deckyfx]

The original topic is here #5170

I seem to found an idea to do this, but extensive testing needs to be done.

In short, seems Realm only checks the naming of the model class constructor, no deep checking there, so the idea is we trick the compiler into thinking your own superclass is Realm.Object<T>

Realmjs version 12.6.2

File 1, BaseModel.tsx

import ORealm, {BSON} from 'realm'; // import Realm as ORealm, so we can export our own Realm namespace

import {DefaultObject} from 'realm/dist/internal'; // import some types

class BaseModel<T = DefaultObject> extends ORealm.Object<T> { // extends from Realm.Object
  _id!: BSON.ObjectId;  // declare base properties that will owned by all models extended from this class
  
  // declare methods that will inherited by the child class
  sayHello() {
    return 'hi';
  }
}

// Export out own realm
export namespace Realm {
  export const Object = BaseModel;
}

Now File 2, Experimental.tsx

import {ObjectSchema} from 'realm';

import {Realm} from './BaseModel'; // import our exported Realm namesmpace

class Experimental extends Realm.Object<Experimental> { // Extends from out own BaseModel
  name!: string; // properties that this class has
  
  // declare schema
  static schema: ObjectSchema = {
    name: 'Experimental',
    properties: {
      _id: 'objectId',

      name: 'string',
    },
    primaryKey: '_id',
  };
}
export default Experimental;

Now to test it

    realmSync.write(() => {
      realmSync.create(Experimental, {
        _id: new BSON.ObjectId(),
        name: 'john doe',
      });
    });

    const data = realmSync.objects(Experimental);
    data.forEach(element => {
      console.log(element.constructor.name, element._id, element.sayHello());
    });

The result will be

Experimental "661c90010c03212e0827568a" hi

To Do

• Nested inheritance, (should be possible by repeating the process)
• Type checking, (I still don't test if Experimental instanceof BaseModel, should be yes tho)

Any other ideas?

[astrahov]

class BaseModel extends Realm.Object

class FileBase extends BaseModel

class FileAudio extends FileBase

....

These cases are worth considering