IMPORTANT

GraQL is prerelease, experimental, and a demonstration piece. Use at your own risk.

Exception Handling

GraphQL is designed to mask underlying exceptions by default. This makes sense, and it's good security practice: there's no sense sending stack traces back to consumers!

However, the messages sent back can be less than helpful.

To assist, GraQL allows you to designate any method within a @GraQLComponent as an exception handler for a given type of Exception.

Example

Given MyCustomException, a subclass of Exception:

class MyCustomException:RuntimeException("Custom exception!")

You can add a @GraQLExceptionHandler within any @GraQLComponent class, providing an exception translation method:

@GraQLExceptionHandler
fun handleValidationException(ex: MyCustomException, builder: GraphqlErrorBuilder<*>) {
    builder
        .message("Whoa nelly! That didn't go as planned!")
        .errorType( ErrorType.DataFetchingException )
}

Further Reading

The Netflix DGS team has published guidelines for how to handle exceptions.

We think they're a good idea, and GraQL's validation integration follows these guidelines.