GraphQL - How to catch "Internal" Apollo/GraphQL errors - Java Spring Boot

Question

I started to work with GraphQL for one week and I could not find out yet how to catch "internal" GraphQL errors like CoercingParseValueException. Because our Frontend use this endpoint to receive some information about shipping. When the schema or a required field is missing then GraphQL itself send an error which just got a message with arbitrary strings which you have to parse at the frontend to understand this message and show the client the correct error.

For our project, we defined a error-model for custom errors. This error-model contains a code field with a self defined code for every situtation like NotFoundException, ValidationException etc.

But how can I catch error from GraphQL and modify them?

Apporaches:

@Component
public class GraphQLErrorHandler implements graphql.servlet.GraphQLErrorHandler {

    @Override
    public List<GraphQLError> processErrors(List<GraphQLError> list) {
       return list.stream().map(this::getNested).collect(Collectors.toList());
    }

    private GraphQLError getNested(GraphQLError error) {
        if (error instanceof ExceptionWhileDataFetching) {
            ExceptionWhileDataFetching exceptionError = (ExceptionWhileDataFetching) error;
            if (exceptionError.getException() instanceof GraphQLError) {
                return (GraphQLError) exceptionError.getException();
            }
        }
        return error;
    }

}

Does not work for me. ProcessErrors it is never called. I am using Spring Boot (Kickstarter Version)

For Custom errors I am using the new feature which was released for 10 days.

@Component("CLASSPATH TO THIS CLASS")
public class GraphQLExceptionHandler {

    @ExceptionHandler({NotFoundException.class})
    GraphQLError handleNotFoundException(NotFoundException e) {
        return e;
    }

    @ExceptionHandler(ValidationException.class)
    GraphQLError handleValidationException(ValidationException e) {
        return e;
    }
}

This approach works perfectly with custom error messages. To use this feature I have to enable the graphql-servlet property exception-handlers-enabled and set it to true. Nevertheless this approach does not catch "internal" Apollo/GraphQL errors even if the ExceptionHandler annotation is defined with Exception.class.

Maybe can help me with this problem?

Many thanks

박진영 박진영 · Accepted Answer · 2020-11-20T02:26:33

try this. you should return ThrowableGraphQLError type for general exception

@ExceptionHandler(Exception::class)
fun handleException(e: Exception): ThrowableGraphQLError {
    log.error("{}", e)
    return ThrowableGraphQLError(e, "Internal Server Error")
}

GraphQL - How to catch "Internal" Apollo/GraphQL errors - Java Spring Boot

1 Answers