Custom error handling not working between Spring Boot GraphQL backend and frontend

Frontend
1

I’m trying to send custom error details from my Spring Boot GraphQL backend to the frontend but it’s not working properly.

When I create a mutation method like this:

@MutationMapping
public Mono<User> testError() {
    return Mono.error(new CustomErrorException("Test error", "Details for frontend"));
}

The frontend receives a generic Apollo error instead of my custom error details:

{
    "errors": [
        {
            "message": "INTERNAL_ERROR for abc123-45",
            "locations": [
                {
                    "line": 1,
                    "column": 2
                }
            ],
            "path": [
                "testError"
            ],
            "extensions": {
                "classification": "INTERNAL_ERROR"
            }
        }
    ],
    "data": {
        "testError": null
    }
}

I also tried extending GraphQLError but still can’t get the custom error info to reach the frontend. What’s the right way to handle this?

2

Interesting issue! Are u running this in dev or production? Spring Boot GraphQL acts differently based on the environment. Also, what’s ur CustomErrorException class look like? Does it implement getExtensions() properly?

3

Spring Boot GraphQL sanitizes error messages by default in production, which is why you’re not seeing your custom errors. You’ll need to create a custom DataFetcherExceptionResolverAdapter to fix this. Make a config class that extends the adapter and override resolveToSingleError to return your CustomErrorException details in the extensions field. Also, make sure your CustomErrorException implements GraphQLError with a proper getExtensions method that returns a map of your custom error data. This way you keep things secure but still send the error info your frontend needs.

4

u might be right about Spring Boot’s error filtering. have you tried using the DataFetcherExceptionResolver? it can help u manage error responses better, so ur custom details get through instead of just that generic error.