Right way to handle errors.

[humb1t]

Hello, thanks a lot for this interesting project for gRPC support in Rust ecosystem.
I'm working on a replacing of tonic with ntex-grpc. One thing that I'm struggling with at the moment is error handling.
What is the ntex-grpc way to handle errors in server?

    #[method(VerifyCredentials)]
    async fn verify_credentials(
        &self,
        VerifyCredentialsRequest { token }: VerifyCredentialsRequest,
    ) -> Result<VerifyCredentialsResponse> {

My idea was to use Result in method definition, but maybe idea in ntex-grpc is to write possible error structures in proto file and use oneof with success/fail structures for response types?

[fafhrd91]

at the moment error handling in server side is not very detailed, you have to return proto response.

if you really want to use ntex-grpc, you have to be prepared to dig in internals. i didnt work on server side api much, it is need more work in term of usability

[fafhrd91]

if you willing to spend time on server side api, i can help. personally, i wont be able to spend much time in near term

[humb1t]

@fafhrd91 thanks a lot. I can contribute and interested in it. Can you please help with defining your ideas or thoughts on it and I will try to implement them.

[fafhrd91]

quick idea is to use Responder style trait, similar to actix-web or ntex.

method call would be something like:

async fn method(&self, req: proto::Request) -> impl Responder<proto::Response>;

then it would be possible to define Responder like:

impl<T, E> Responder<Result<T, E>> for proto::Response 
where
   T: Into<proto::Response>
   E: Into<proto::Response>
{
}

also Into could be replaced with TryInto, so failed conversion could be treated as grpc level error

[fafhrd91]

this is just an idea, feel free to design something more interesting

[humb1t]

I think it's a good idea. I will start working on it late March, early April.

[fafhrd91]

added simple response error handling Result<Method::Output, impl IntoMethod::Output>