FederationSchemaFactory does not support custom DataFetcherExceptionResolver

[ivandedkov]

Hello!
When I try to register my own DataFetcherExceptionResolver in context, using federation annotations as EntityMapping annotation, FederationSchemaFactory ignores it, because it uses its ExceptionResolver. The reason - FederationSchemaFactory extends AnnotatedControllerDetectionSupport, and it registers only AnnotatedControllerExceptionResolver as single ExceptionResolver. For example using GraphQlSource.Builder, using spring without federation, it registers exception resolvers as list. And when I throw exception under native controller annotations as SchemaMapping annotation or QueryMapping annotation, it catches all my exceptions and puts into my custom resolvers.

According to it, under federation annotations I am able to use only GraphQlExceptionHandler annotation method way

My request is to add supporting list of exception resolvers into FederationSchemaFactory as it did in GraphQlSource.Builder

[rstoyanchev]

DataFetcherExceptionResolvers configured in GraphQlSource.Builder are used to implement a graphql.execution.DataFetcherExceptionHandler, which is invoked by GraphQL Java when a DataFetcher throws an exception.

For annotated controller methods, we also use a (single) DataFetcherExceptionResolver to apply @GraphQlExceptionHandler methods at the point of controller method invocation, i.e. not even letting the exception propagate to GraphQL Java, if it can be handled in place with knowledge of the controller method that raised the exception.

In other words exception handling is applied at two different levels. For federation support, the EntityDataFetcher itself is a DataFetcher and therefore subject to GraphQL Java exception handling, so any custom DataFetcherExceptionResolver would still apply, but you probably want it to apply at the level of a specific entity.

We could add support for registering custom DataFetcherExceptionResolvers on FederationSchemaFactory, but could you explain why you can't use annotated exception handler methods? That's a more flexible and expressive mechanism.

[ivandedkov]

Because I want to resolve exceptions in general point. In other words, @GraphQlExceptionHandler makes me to use it in every controller class, but sometimes I dont have opportunities to change controller code. To build my spring starter with common error handling, I am not able to do it doe to hardcode exception resolver as AnnotatedControllerDetectionSupport

[rstoyanchev]

Have you tried putting @GraphQlExceptionHandlers in an @ControllerAdvice class? That should apply globally to any controller and should work just the same since it comes from the base class AnnotatedControllerDetectionSupport.

[ivandedkov]

Yeah.. It works. I am sorry, I did't catch about it before. Thank u! Issue can be closed