Loopback4 hasMany not return the link array

Question

I just try to use the hasMany relationship according to the loopback4 documentation .but it's not working as expected.

My Bus Model =>

export class Bus extends Entity {
  @property({
    type: 'number',
    id: true,
    generated: true,
  })
  id?: number;

  @hasMany(() => BusStation, {keyTo: 'busId'})
  stations?: BusStation[];

  constructor(data?: Partial<Bus>) {
    super(data);
  }
}

export interface BusRelations {
  // describe navigational properties here
}

export type BusWithRelations = Bus & BusRelations ;

Bus Station Model =>

export class BusStation extends Entity {
  @property({
    type: 'number',
    id: true,
    generated: true,
  })
  id?: number;

  @property({
     type: 'number',
  })
  busId: number;

  @property({
    type: 'string',
    required: true,
  })
  name: string;

  constructor(data?: Partial<BusStation>) {
    super(data);
  }
}

export interface BusStationRelations {
  // describe navigational properties here
}

export type BusStationWithRelations = BusStation & BusStationRelations;

Bus Repository =>

export class BusRepository extends DefaultCrudRepository<
  Bus,
  typeof Bus.prototype.id,
  BusRelations
> {
  public stations: HasManyRepositoryFactory<
    BusStation,
    typeof Bus.prototype.id
  >;

  constructor(
    @inject('datasources') dataSource: MyDataSource,
    @repository.getter('BusStationRepository')
    busStationRepositoryGetter: Getter<BusStationRepository>,
  ) {
    super(Bus, dataSource);
    this.stations = this.createHasManyRepositoryFactoryFor(
      'stations',
      busStationnRepositoryGetter,
    );
  }
}

My Expected Get Response of Bus =>

{
" id":1,
"stations":[
    {
        "id":1,
        "busId":1,
        "name":"Station 1"
    }
]
}

I did the exactly same with the documentation but why I can't get the response as I expected. Please May I know what I am missing?

I saw that some solution is to create another controller to connect these two models. Is it the only way? if yes, what is the reason for the hasMany?

Answer 1

in repository you have to include inclusion resolver under

this.stations = this.createHasManyRepositoryFactoryFor('stations',busStationnRepositoryGetter,);

like this

this.registerInclusionResolver('stations', this.stations.inclusionResolver);

on the other hand, you can use relation generator to avoid all this stuff.