ResolveProperty('__resolveType') not working with type-graphql

The last few days I migrated our project to use type-graphql with nest. I managed to migrate everything, but I am still stuck on one thing. Providing a custom __typename doesn’t seem to work.

Here is my resolver:

@Resolver(ServiceProvider)
export class ServiceProviderResolvers {
    constructor(private readonly searchService: SearchService) {}

    @Query(() => [ServiceProvider])
    all(): Promise<ServiceProvider[]> {
        return this.searchService.all();
    }

    @ResolveProperty('__resolveType')
    resolveType(obj: ServiceProvider): string {
         return obj.type;
    }

    @ResolveProperty()
    test(obj: ServiceProvider): string {
         return obj.type;
    }
}

But the resolveType doesn’t seem to be called, where test method is called if I query for test field.

I also tried to use some interface like suggested 19majkel94 (from type-graphql) but still doesn’t work: https://github.com/19majkel94/type-graphql/issues/181#issuecomment-475166589

Is there any way to customize __typename with nest using type-graphql?

[kamilmysliwiec]

See https://typegraphql.ml/docs/interfaces.html

[michelcve]

@kamilmysliwiec While creating a test project, I finally figured it out.

In my tsconfig.json I had target: es5. This works fine, until you start using @ResolveProperty. The resolution for this is switching target to target: es6.