protoc generated c# code does not compile

Question

I'm not a Windows/Visual Studio person, so maybe I'm doing something obviously wrong. I'm going to have to write a gRPC wrapper around a library for .NET 4.8. That means I won't be able to use the newer grpc-dotnet and should use the older Grpc.Core library.

As far as I can tell, I need to manually generate the C# code using protoc, so I'm using this command:

protoc --proto_path=. --csharp_out=grpc .\greet.proto --grpc_out=grpc --plugin=protoc-gen-grpc="C:\users\foo\.nuget\packages\grpc.tools0円.5.0\tools\grpc_csharp_plugin.exe"

I get two files Greet.cs and GreetGrpc.cs which I add to my Visual Studio project. I've also added some nuggets I thought are relevant (Google.Protobuf, Grpc.Core, Grpc.Tools, Grpc.Net.Client). The generated code does not compile though.

For example this line:

static readonly Marshaller<global::Greet.HelloRequest> __Marshaller_HelloRequest = Marshallers.Create((arg) => arg.ToByteArray(), global::Greet.HelloRequest.ParseFrom);

would cause an error:

'HelloRequest' does not contain a definition for 'ParseFrom'

Also this line:

static readonly Method<global::Greet.PrepareRequest, global::Greet.PrepareResponse> __Method_Prepare = new Method<global::Greet.PrepareRequest, global::Greet.PrepareResponse>(
 MethodType.Unary,
 "Prepare",
 __Marshaller_PrepareRequest,
 __Marshaller_PrepareResponse);

causes:

There is no argument given that corresponds to the required parameter 'responseMarshaller' of 'Method<PrepareRequest, PrepareResponse>.Method(MethodType, string, string, Marshaller, Marshaller)'

I would appreciate any help.

• phuzi: ".nuget\packages\grpc.tools0円.5.0"! Is that actually the 0.5.0 version of GRPC Tools from 2015? I would seriously consider updating that to something a bit more recent.
• Elektito: Looking at Visual Studio, the installed version is 2.68.1. I think I should poke around to see where that resides in the file system.
• phuzi: Yeah, if you have a later version installed you should try updating the --plugin=protoc-gen-grpc= option to refer to a later version.
• Elektito: @phuzi I can't seem to find the newer version. Neither Windows Search nor google is being helpful. Can you tell me where I can download the latest version of that plugin?
• Elektito: Found it. For some reason, I thought there's no other version in that directly, but there is one. Update to the latest version, and it's fixed. Thanks a lot!

Answer 1

Your protoc command appears to be using an ancient version of the csharp grpc plugin that was released way back in 2015! I would guarantee that the generated C# has come a long way since then.

--plugin=protoc-gen-grpc="C:\users\foo\.nuget\packages\grpc.tools0円.5.0\tools\grpc_csharp_plugin.exe"

You've stated in the comments that the project/solution is using the latest version (currently 2.68.1). You should update the --plugin=protoc-gen-grpc= option to refer to the installed version so that the generated C# code is in-sync with the installed GRPC.Core package.

C:\users\foo\.nuget\packages\grpc.tools2円.68.1 directory.