Hi, I have a question regarding Spring graphQL data/error management. I have a use case where I want to return several results, including the error ones, as a Union. something like this:

extend type Mutation {
userCreate(): UserCreatePayload
}
union UserCreatePayload = UserCreated | UserAlreadyExists

I have a MutationsResolver that handles the

userCreate

mutation by calling a

UserService

that is transactional. When trying to create a user, if the user already exists, I'm throwing a

UserAlreadyExist

Exception that is handled in the mutation resolver with a try/catch block and then mapped to the UserAlreadyExists type in graphql. The problem is that as the UserService is transactional, whenever I throw the exception, the transaction is marked a rollbackOnly by spring (which is good) and then the graphql flow goes through the DefaultGraphQLErrorHandler that finally return an error to the end user. I would like to have the exactly same behavior except for the graphql error handler returning a GraphqlError. Instead I want to return the

UserAlreadyExists

type I defined in the graphql schema. Is there anyway to do so? (I do not want to use sealed classes instead of exceptions in the service as the code gets dirty) Thanks!

which GraphQL server implementation are you using?

graphql-java

graphql-java

is a GraphQL implementation but doesn't define a server (as that is a higher level concept) -> some libs built on top of

graphql-java

providing server functionality •

graphql-kotlin

(I'm one of the maintainers of it) •

graphql-java-kickstart

•

netflix-dgs

•

spring-graphql

yes.

graphql-java-kickstart

is the one I'm using.

I'd assume you could just return the

UserAlreadyExist

from your try/catch block in the reesolver?

I'm doing that. The problem is that as spring marked the transaction as rollbackOnly, then the flow goes through the DefaultGraphQLErrorHandler and the end user is getting the graphql error instead of the data

sounds like its caused by Spring and not really

graphql-java-kickstart

That might help. Thank you. I will let you know if it worked.