make jsonpb marshaler emit defaults (#3)

add `-emit-defaults` flag so that output will include default values (e.g. "false" for boolean flags)

cmd/grpcurl/grpcurl.go

@@ -12,6 +12,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/golang/protobuf/jsonpb"
+	"github.com/golang/protobuf/proto"
 	"github.com/jhump/protoreflect/desc"
 	"github.com/jhump/protoreflect/grpcreflect"
 	"golang.org/x/net/context"
@@ -64,6 +66,8 @@ var (
 		`The maximum total time the operation can take. This is useful for
     	preventing batch jobs that use grpcurl from hanging due to slow or bad
     	network links or due to incorrect stream method usage.`)
+	emitDefaults = flag.Bool("emit-defaults", false,
+		`Emit default values from JSON-encoded responses.`)
 	verbose = flag.Bool("v", false,
 		`Enable verbose output.`)
 )
@@ -442,12 +446,17 @@ func (*handler) OnReceiveHeaders(md metadata.MD) {
 	}
 }
 
-func (h *handler) OnReceiveResponse(rsp json.RawMessage) {
+func (h *handler) OnReceiveResponse(resp proto.Message) {
 	h.respCount++
 	if *verbose {
 		fmt.Print("\nResponse contents:\n")
 	}
-	fmt.Println(string(rsp))
+	jsm := jsonpb.Marshaler{EmitDefaults: *emitDefaults, Indent: "  "}
+	respStr, err := jsm.MarshalToString(resp)
+	if err != nil {
+		fail(err, "failed to generate JSON form of response message")
+	}
+	fmt.Println(respStr)
 }
 
 func (h *handler) OnReceiveTrailers(stat *status.Status, md metadata.MD) {

grpcurl.go

@@ -263,7 +263,7 @@ type InvocationEventHandler interface {
 	// OnReceiveHeaders is called when response headers have been received.
 	OnReceiveHeaders(metadata.MD)
 	// OnReceiveResponse is called for each response message received.
-	OnReceiveResponse(json.RawMessage)
+	OnReceiveResponse(proto.Message)
 	// OnReceiveTrailers is called when response trailers and final RPC status have been received.
 	OnReceiveTrailers(*status.Status, metadata.MD)
 }
@@ -384,14 +384,8 @@ func invokeUnary(ctx context.Context, stub grpcdynamic.Stub, md *desc.MethodDesc
 
 	handler.OnReceiveHeaders(respHeaders)
 
-	var respStr string
 	if stat.Code() == codes.OK {
-		jsm := jsonpb.Marshaler{Indent: "  "}
+		handler.OnReceiveResponse(resp)
-		respStr, err = jsm.MarshalToString(resp)
-		if err != nil {
-			return fmt.Errorf("failed to generate JSON form of response message: %v", err)
-		}
-		handler.OnReceiveResponse(json.RawMessage(respStr))
 	}
 
 	handler.OnReceiveTrailers(stat, respTrailers)
@@ -447,14 +441,8 @@ func invokeClientStream(ctx context.Context, stub grpcdynamic.Stub, md *desc.Met
 		handler.OnReceiveHeaders(respHeaders)
 	}
 
-	var respStr string
 	if stat.Code() == codes.OK {
-		jsm := jsonpb.Marshaler{Indent: "  "}
+		handler.OnReceiveResponse(resp)
-		respStr, err = jsm.MarshalToString(resp)
-		if err != nil {
-			return fmt.Errorf("failed to generate JSON form of response message: %v", err)
-		}
-		handler.OnReceiveResponse(json.RawMessage(respStr))
 	}
 
 	handler.OnReceiveTrailers(stat, str.Trailer())
@@ -502,12 +490,7 @@ func invokeServerStream(ctx context.Context, stub grpcdynamic.Stub, md *desc.Met
 			}
 			break
 		}
-		jsm := jsonpb.Marshaler{Indent: "  "}
+		handler.OnReceiveResponse(resp)
-		respStr, err := jsm.MarshalToString(resp)
-		if err != nil {
-			return fmt.Errorf("failed to generate JSON form of response message: %v", err)
-		}
-		handler.OnReceiveResponse(json.RawMessage(respStr))
 	}
 
 	stat, ok := status.FromError(err)
@@ -588,13 +571,7 @@ func invokeBidi(ctx context.Context, cancel context.CancelFunc, stub grpcdynamic
 			}
 			break
 		}
-		jsm := jsonpb.Marshaler{Indent: "  "}
+		handler.OnReceiveResponse(resp)
-		respStr, err := jsm.MarshalToString(resp)
-		if err != nil {
-			return fmt.Errorf("failed to generate JSON form of response message: %v", err)
-		}
-
-		handler.OnReceiveResponse(json.RawMessage(respStr))
 	}
 
 	if se, ok := sendErr.Load().(error); ok && se != io.EOF {

grpcurl_test.go

@@ -576,8 +576,13 @@ func (h *handler) OnReceiveHeaders(md metadata.MD) {
 	h.respHeaders = md
 }
 
-func (h *handler) OnReceiveResponse(msg json.RawMessage) {
+func (h *handler) OnReceiveResponse(msg proto.Message) {
-	h.respMessages = append(h.respMessages, string(msg))
+	jsm := jsonpb.Marshaler{Indent: "  "}
+	respStr, err := jsm.MarshalToString(msg)
+	if err != nil {
+		panic(fmt.Errorf("failed to generate JSON form of response message: %v", err))
+	}
+	h.respMessages = append(h.respMessages, respStr)
 }
 
 func (h *handler) OnReceiveTrailers(stat *status.Status, md metadata.MD) {