jsonpb: Handle Struct and NullValue WKTs.

jsonpb/jsonpb.go

@@ -41,6 +41,7 @@ package jsonpb
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"reflect"
@@ -125,6 +126,10 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent string
 			out.write(x)
 			out.write(`s"`)
 			return out.err
+		case "Struct":
+			// Let marshalValue handle the `fields` map.
+			// TODO: pass the correct Properties if needed.
+			return m.marshalValue(out, &proto.Properties{}, s.Field(0), indent)
 		case "Timestamp":
 			// "RFC 3339, where generated output will always be Z-normalized
 			//  and uses 3, 6 or 9 fractional digits."
@@ -138,6 +143,17 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent string
 			out.write(x)
 			out.write(`Z"`)
 			return out.err
+		case "Value":
+			// Value has a single oneof.
+			kind := s.Field(0)
+			if kind.IsNil() {
+				// "absence of any variant indicates an error"
+				return errors.New("nil Value")
+			}
+			// oneof -> *T -> T -> T.F
+			x := kind.Elem().Elem().Field(0)
+			// TODO: pass the correct Properties if needed.
+			return m.marshalValue(out, &proto.Properties{}, x, indent)
 		}
 	}
 
@@ -304,6 +320,19 @@ func (m *Marshaler) marshalValue(out *errWriter, prop *proto.Properties, v refle
 		return out.err
 	}
 
+	// Handle well-known types.
+	// Most are handled up in marshalObject (because 99% are messages).
+	type wkt interface {
+		XXX_WellKnownType() string
+	}
+	if wkt, ok := v.Interface().(wkt); ok {
+		switch wkt.XXX_WellKnownType() {
+		case "NullValue":
+			out.write("null")
+			return out.err
+		}
+	}
+
 	// Handle enumerations.
 	if !m.EnumsAsInts && prop.Enum != "" {
 		// Unknown enum values will are stringified by the proto library as their

jsonpb/jsonpb_test.go

@@ -40,6 +40,7 @@ import (
 	pb "github.com/golang/protobuf/jsonpb/jsonpb_test_proto"
 	proto3pb "github.com/golang/protobuf/proto/proto3_proto"
 	durpb "github.com/golang/protobuf/ptypes/duration"
+	stpb "github.com/golang/protobuf/ptypes/struct"
 	tspb "github.com/golang/protobuf/ptypes/timestamp"
 	wpb "github.com/golang/protobuf/ptypes/wrappers"
 )
@@ -321,6 +322,12 @@ var marshalingTests = []struct {
 	{"proto2 extension", marshaler, realNumber, realNumberJSON},
 
 	{"Duration", marshaler, &pb.KnownTypes{Dur: &durpb.Duration{Seconds: 3}}, `{"dur":"3.000s"}`},
+	{"Struct", marshaler, &pb.KnownTypes{St: &stpb.Struct{
+		Fields: map[string]*stpb.Value{
+			"one": &stpb.Value{Kind: &stpb.Value_StringValue{"loneliest number"}},
+			"two": &stpb.Value{Kind: &stpb.Value_NullValue{stpb.NullValue_NULL_VALUE}},
+		},
+	}}, `{"st":{"one":"loneliest number","two":null}}`},
 	{"Timestamp", marshaler, &pb.KnownTypes{Ts: &tspb.Timestamp{Seconds: 14e8, Nanos: 21e6}}, `{"ts":"2014-05-13T16:53:20.021Z"}`},
 
 	{"DoubleValue", marshaler, &pb.KnownTypes{Dbl: &wpb.DoubleValue{Value: 1.2}}, `{"dbl":1.2}`},

jsonpb/jsonpb_test_proto/Makefile

@@ -30,4 +30,4 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 regenerate:
-	protoc --go_out=Mgoogle/protobuf/duration.proto=github.com/golang/protobuf/ptypes/duration,Mgoogle/protobuf/timestamp.proto=github.com/golang/protobuf/ptypes/timestamp,Mgoogle/protobuf/wrappers.proto=github.com/golang/protobuf/ptypes/wrappers:. *.proto
+	protoc --go_out=Mgoogle/protobuf/duration.proto=github.com/golang/protobuf/ptypes/duration,Mgoogle/protobuf/struct.proto=github.com/golang/protobuf/ptypes/struct,Mgoogle/protobuf/timestamp.proto=github.com/golang/protobuf/ptypes/timestamp,Mgoogle/protobuf/wrappers.proto=github.com/golang/protobuf/ptypes/wrappers:. *.proto