Custom array function doesn't work

[ileodo]

Description

similar to #216, when I am trying run the example code (example3) below, it's complaining photo.albums.findByName is not a function

import 'es6-shim';
import 'reflect-metadata';

import { Type, Transform, Expose } from 'class-transformer';
import { plainToInstance, plainToClass } from 'class-transformer';
class Album {
    id: string;

    name: string;
}

class AlbumArray extends Array<Album> {
    findByName(name: string) {
        return this.find(album => album.name === name);
    }
}
class Photo {
    id: string;
  
    filename: string;
  
    description: string;
  
    tags: string[];
  
    @Type(() => Album)
    albums: AlbumArray;
  }


  let photoJson = {
    id: '1',
    filename: 'myphoto.jpg',
    description: 'about my photo',
    tags: ['me', 'iam'],
    albums: [
      {
        id: '1',
        name: 'My life',
      },
      {
        id: '2',
        name: 'My young years',
      },
    ],
  };
  
  let photo = plainToClass(Photo, photoJson);
  console.log('deserialized object: ', photo);
  console.log('-----------------------------');
  console.log('Trying to find album: ', photo.albums.findByName('My life'));
  console.log('-----------------------------');

Expected behavior

print out the return of the findByName

Actual behavior

photo.albums.findByName is not a function

[aboqasem]

Firstly, you are not transforming the value of albums to AlbumArray it will remain Album[]:

@Transform(({ value }) => new AlbumArray(...value))

Secondly, something is wrong with this inheritance in TypeScript. This works fine in the browser, not in TypeScript:

class PowerArray extends Array {
  isEmpty() {
    return this.length === 0;
  }
}

const arr = new PowerArray(1, 2, 5, 10, 50);
console.log(arr.isEmpty());

EDIT:

Works fine on TS Playground but not on CodeSandbox.

[ileodo]

looks like it's not aligned with the documentation: https://github.com/typestack/class-transformer#working-with-arrays

and official example: https://github.com/typestack/class-transformer/blob/develop/sample/sample3-custom-arrays/Photo.ts#L15

[colecrouter]

It seems like @Type() is applying the intended "child type" to the parent object?

I'm working with Maps, and I've resorted to just using @ValidateNested() and manually re-assigning my maps as proper Map<K,V>()s.