Cannot import external proto file - Works in commandline but not in .net core 3 RC1

Question

I'm moving my gRPC app from .net framework to .net core

I have two main proto files as follows

/Proto/common/common.proto
/Proto/my-service.proto

my-service.proto importing common.proto as simple as this:

common.proto

syntax="proto3";
package common;
option csharp_namespace = "Koko.Wawa";

message ValidationFailure {
    string property_name = 1;
    string error_message = 2;
}
message ValidationResult {
    bool is_valid = 1;
    repeated ValidationFailure errors = 2;
}

my-service.proto

syntax="proto3";
package google.protobuf;
option csharp_namespace = "Koko.Wawa";

import "common/common.proto"; // << in gRPC .net Core Template it gives error 

message CreateDraftPackageRequest {
  string package_type = 1;
  repeated int32 client_ids = 2;
}
message CreateDraftPackageResponse {
    int32 id = 1;
    string package_type = 2;
    int64 created_on = 3;
    int32 package_delivery_status = 4;
    common.ValidationResult validation_result = 5;
}
service ExportPackageService {
    rpc CreateDraftPackage (CreateDraftPackageRequest) returns (CreateDraftPackageResponse);
}

In a Powershell command, I used protoc command line to generate my C# classes. Also, I modified it to make it work with .net core also.

$exe = "${env:USERPROFILE}\.nuget\packages\grpc.tools\2.24.0-pre1\tools\windows_x64\protoc.exe"
$plugin = "${env:USERPROFILE}\.nuget\packages\grpc.tools\2.24.0-pre1\tools\windows_x64\grpc_csharp_plugin.exe"
& $exe -I .\Protos\Common --csharp_out .\Output\Common .\Protos\Common\common.proto --grpc_out .\Output\Common --plugin=protoc-gen-grpc=$plugin --csharp_opt=file_extension=.g.cs --grpc_opt=internal_access
& $exe -I .\Protos --csharp_out .\Output .\Protos\export-package-service.proto --grpc_out .\Output --plugin=protoc-gen-grpc=$plugin --csharp_opt=file_extension=.g.cs --grpc_opt=internal_access

Everything works perfectly with this approach. But I tried to depend on the new gRPC template in .net core 3, you will keep getting a File not found an error! In

import "common/common.proto"; // <<<<<

Answer 1

Change import to the path relative to the project root:

import "Proto/Common/common.proto"; 

If you still want to use exe directly, change -I argument to the project dir, eg .\:

& $exe -I .\ --csharp_out .\Output .\Protos\export-package-service.proto --grpc_out .\Output --plugin=protoc-gen-grpc=$plugin --csharp_opt=file_extension=.g.cs --grpc_opt=internal_access