Adding Emit Defaults Option

[James-Bartman]

Problem Statement

When using gRPC UI, I came across a scenario where I did not want default values emitted to the Response tab. While gRPCurl has an option to enable/disable emit-defaults, gRPC UI does not since the call it makes to gRPCurl hard-codes emit-defaults to true. Thus, there was an inconsistency between these two closely related tools.

Example Proto File

service Greeter {
   rpc SayHello (HelloRequest) returns (HelloReply);
}

message HelloRequest {
   string name = 1;
}

message TwoNums {
   int32 abc = 1;
   int32 xyz = 2;
}

message HelloReply {
   oneof HelloReplies {
      TwoNums nums = 1;
      int32 num = 2;
   }
   string answer = 3;
}

Sample Server Implementation - Written in Go

server.txt

gRPC UI Output

{
  "nums": {
    "abc": 3,
    "xyz": 3
  },
  "answer": ""
}

gRPCurl Output with -emit-defaults=false

{
  "nums": {
    "abc": 3,
    "xyz": 3
  }
}

Fix

• Added emit-defaults flag to the cmd/grpcui.go file.
• Set a global variable in handlers.go to accept value of emit-defaults flag.
• The default value of this flag is true, to preserve existing behavior

grpcui -h
...
-emit-defaults
        Emit default values for JSON-encoded responses. (default true)
...

gRPC UI Output After Fix with -emit-defaults=false

{
  "nums": {
    "abc": 3,
    "xyz": 3
  }
}

[James-Bartman]

Just bumping this but not sure exactly who to notify. @dragonsinth @gpassini