使用 Grpc.Tools 和 Protoc 插件生成额外的 C# 文件

Question

I am using Grpc.Tools (2.38.1) to generate C# types and gRPC stubs from a Test.proto file containing some service definitions.

To do this I have the following in my project's .csproj file:

<ItemGroup>
    <Protobuf Include="**/*.proto" />
</ItemGroup>

This is all working fine: my Test.proto gets compiled to Test.cs and TestGrpc.cs in the obj/Debug folder of my project. The types within them can be referenced from within other types in the project.

But I need to create a WCF interface for the service too, so I thought I could generate this using a custom Protoc plug-in. So I wrote a simple Protoc plug-in that writes out a TestWcf.cs file containing an interface. I then placed this plug-in executable on my path named protoc-gen-blah.exe and updated the entry in the .csproj file to this:

<ItemGroup>
    <Protobuf Include="**/*.proto" AdditionalProtocArguments="--blah_out=obj\Debug" />
</ItemGroup>

This correctly creates the C# file, TestWcf.cs , with my interface in: fantastic.

The problem is that my interface within TestWcf.cs cannot be referenced from other types in the project unless I manually include the generated file in the project: something I do not have to do with the other generated files.

Whilst none of the files are included in the project by default―I have to enable 'Show All Files' to see them― Test.cs and TestGrpc.cs have arrows beside them in the Solution Explorer that allow them to be expanded to reveal the types inside. TestWcf.cs does not have this arrow. So Visual Studio is somehow aware that Test.cs and TestGrpc.cs are source code files.

Does anyone know what I need to do for my generated file to be automatically recognised by Visual Studio like the other two files are?

I suspect it has something to do with this part of the Grpc.Tools build target , as I noticed my TestWcf.cs file is not included in the files deleted by the Grpc.Tools clean either, but I can't see why it does not consider my generated file to be C#.

When I build, this is the Protoc call:

D:\...\Src\packages\Grpc.Tools.2.38.1\tools\windows_x86\protoc.exe --csharp_out=obj\Debug ⤶
--plugin=protoc-gen-grpc=D:\...\Src\packages\Grpc.Tools.2.38.1\tools\windows_x86\grpc_csharp_plugin.exe ⤶
--grpc_out=obj\Debug --proto_path=D:\...\Src\packages\Grpc.Tools.2.38.1\build\native\include ⤶
--proto_path=. --dependency_out=obj\Debug\xxxx_Test.protodep --error_format=msvs --blah_out=obj\Debug ⤶
Test.proto

The dependency file looks like this:

obj\Debug/Test.cs \
obj\Debug/TestGrpc.cs \
obj\Debug/TestWcf.cs: Test.proto

Thanks.

Answer 1

I believe the problem is caused some logic in Grpc.Tools that informs MSBuild of the files that have been generated:

public override string[] GetPossibleOutputs(ITaskItem protoItem)
{
    ...     
    var outputs = new string[doGrpc ? 2 : 1];
    ...
    outputs[0] = Path.Combine(outdir, filename) + ".cs";

    if (doGrpc)
    {
        ...
        outputs[1] = Path.Combine(grpcdir, filename) + "Grpc.cs";
    }
    return outputs;
}

This code only caters for two files being generated from a Protocol Buffer source ( name.proto ): the Protocol Buffers code generation ( name.cs ) and the gRPC code generation ( nameGrpc.cs ). It is not picking up the additional file and informing MSBuild that it exists, hence Visual Studio does not consider it to be code.

There is no away around this short of changing the Grpc.Tools code.