Hey, I'm trying to register a `FederatedTypeResolver` in a Boot applications, but how ever I do it I...

# graphql-kotlin

[herder]

Hey, I'm trying to register a FederatedTypeResolver in a Boot applications, but how ever I do it I can't get it to kick in. I wonder if I'm misunderstanding somehing - I have a simple schema like this

@KeyDirective(FieldSet("id"))
data class MySubThing(val id: Int?, val extraThing: String)

data class MyThing(@ExtendsDirective val id: String, val subThings: List<MySubThing>) {
}

, and register this resolver class as a bean:

class MySubThingResolver: FederatedTypeResolver<MySubThing> {
    override suspend fun resolve(
      environment: DataFetchingEnvironment,
      representations: List<Map<String, Any>>
    ): List<MySubThing?> {
      return representations.stream().map {
        MySubThing(it["id"]?.toString()?.toInt(), "WOOOP")
      }.collect(Collectors.toList())
    }

But I can't get the resolver to be called however I try. What is the recommended way of registering resolvers for a schema in a Boot app?
(I have set the graphql.federation.enabled to true )

[Dariusz Kuc]

hi 👋 I believe in 3.x you have to explicitly create FederatedTypeRegistry bean that holds the mapping for those resolvers (https://github.com/ExpediaGroup/graphql-kotlin/blob/3.x.x/graphql-kotlin-spring-se[…]expediagroup/graphql/spring/FederatedSchemaAutoConfiguration.kt)

[Dariusz Kuc]

*in 4.x we simplified that to automatically wire up the federated resolvers

[herder]

Yeah, I did that too, but it wasn't called anyway.

@Bean
  fun federatedTypeRegistry(federatedTypeResolvers: List<FederatedTypeResolver<*>>): FederatedTypeRegistry {
    return FederatedTypeRegistry(federatedTypeResolvers.map { "MySubThing" to it }.toMap())
  }

[herder]

But the principle I'm using is what is recommended at least, right?

[herder]

The schema is ok, and the resolver should kick in if everything is set up correclty?

[herder]

I'll bump to 4.x and see if it works better

[Dariusz Kuc]

i think your schema might be missing some directives

[herder]

That might very well be true - I have moved stuff around wildly to experimient 🙂

[Dariusz Kuc]

if i remember right all federated entities will need @key (which is missing on MyThing

[Dariusz Kuc]

federated schema generator hook will validate it

[Dariusz Kuc]

so if it can generate the schema (and it should generate the schema without the resolvers) it should be good

[herder]

Yeah, I did get an error with some variants of my annotation placements, so it seems to validate

[Dariusz Kuc]

@KeyDirective(fields = FieldSet("id"))
@ExtendsDirective
class MyThing(@ExternalDirective val id: String, val subThings: List<MySubThing>)

[herder]

Made no difference with 3.7.0 - i'll check the 4.x branch and get back. But thanks for the confirmation that I'm not totally off!