Filter By Nested Federation Object

Hey guys, I have a problem for long time and I can still not figure out how to solve it:

Basically I have two Services one Service that has the Object StoreItem and the other one has the Object TradeItem. Both Services are running on a Apollo Federation Server.

@ObjectType()
@Directive('@key(fields: "tradeItem_id")')
@Entity()
export class StoreItem extends BaseEntity {
  @Field(() => ID)
  @Index()
  @PrimaryGeneratedColumn('uuid')
  _id: string;

  @Field()
  @Column('uuid')
  tradeItem_id: string;

}
@ObjectType({ description: 'Trade Item' })
@Directive('@key(fields: "_id")')
@Entity()
export class TradeItem extends BaseEntity {
  @Field(() => ID)
  @PrimaryGeneratedColumn('uuid')
  _id: string;

  @Column()
  isAvailable: boolean;
}

This is my Resolver on the TradeItem Service

@Resolver(of => StoreItem)
export class StoreItemResolver {
  private logger = new Logger('StoreItemResolver');
  constructor(private readonly tradeItemService: TradeItemService) {}

  // Returns the TradeItem based in StoreItem

  @ResolveField(() => TradeItem)
  async tradeItem(
    @Parent() storeItem: StoreItem,
    @Context('tradeItemLoader')
    tradeItemLoader: DataLoader<string, TradeItem>,
  ): Promise<TradeItem | Error> {
    const id = storeItem.tradeItem_id as unknown;
    return tradeItemLoader.load(id as string);
  }
}

Example : What I want to do is, I want to return all StoreItems where isAvailable is true. I do not really know how to do this because the Object is build on the Federation Server.

So if I for example build a search like getAvailableStoreItems.

I have 5 StoreItems with 5 nested TradeItem where isAvailable is true. That is not a problem. He will return all StoreItems with the nested TradeItem.

The problem is if just 2 TradeItems are true he will return null. What I want is that he recognize that only 2 TradeItems are true therefore he has to filter out the other 3 StoreItems.

But I do not know where to implement this logic or how it works in general. Somehow it is just magic that the tradeItem object appears inside the StoreItem Object. I tried stuff in the ResolverField on the TradeItem Service. But no success. I use NestJS