This package adds a generic RpcException<T> type to gRPC, and provides an Interceptor that propagates the typed exception from server to client, providing similar functionality to WCF's FaultException.

The T type parameter is constrained to Protobuf types; that is, types that implement Google.Protobuf.IMessage. You will need to define error messages in your .proto file to use with it.

message MyCustomError {
    string reason = 1;
}

In your server code, you can throw an exception like this:

var error = new MyCustomError { Reason = "Bork bork bork" };
throw new RpcException<MyCustomError>(error);

You can catch this specific exception in your client code like this:

try
{
    var response = await client.GetThing(request);
}
catch (RpcException<MyCustomError> ex)
{
    Console.WriteLine(ex.Detail.Reason);
}
catch (RpcException ex)
{
    // Handle other exceptions
}

This gives you more granular control over exception handling, as well as more useful information included in the exceptions.

On the server, you can add the interceptor to all services in a gRPC application using the options callback for AddGrpc:

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc(options =>
    {
        // Add the interceptor to all services
        options.Interceptors.Add<TypedExceptionInterceptor>();
    });
}

For the client, if you're creating it manually you need to use the Intercept method on GrpcChannel to create a CallInvoker you can then pass to the client constructor:

var invoker = GrpcChannel.ForAddress(httpClient.BaseAddress, new GrpcChannelOptions
    {
        HttpClient = httpClient
    })
    .Intercept(new TypedExceptionInterceptor());

var client = new MyService.MyServiceClient(invoker);

If you're using the client factory in a .NET Core application, you can add the interceptor when registering the service:

services
    .AddGrpcClient<MyService.MyServiceClient>(o =>
    {
        o.Address = new Uri("https://localhost:5001");
    })
    .AddInterceptor(() => new TypedExceptionInterceptor());