Errors

The above examples show how to handle a successful RPC when the client successfully receives a response from the server. But what happens if our request is invalid? Or if there is a bug in the server that results in an error?

Earlier in the chapter, when we were creating the Go server, we introduced the gRPC error codes: sixteen error codes that servers can use when categorizing an error. The Go server has a simple example: if the client requests an unknown film ID, it sends back a Not Found error code.

In RPC clients, such an error will manifest as an exception:

Ruby

# Our server is hard-coded to know about IDs 4-6. It does
# not know about ID 7.
request = GetFilmRequest.new(id: '7')
begin
  response = stub.get_film(request)
  puts response.inspect
rescue GRPC::BadStatus => e
  # RPC exceptions have a numeric 'code' field (the gRPC error code)
  # and a string 'details' (the message supplied by the server)
  puts "failed: #{e.details} (code...