fix FieldMask are converted to/from lower-camel naming conventions. (#1724)

encoding/form/form.go

@@ -34,7 +34,7 @@ func (c codec) Marshal(v interface{}) ([]byte, error) {
 	var vs url.Values
 	var err error
 	if m, ok := v.(proto.Message); ok {
-		vs, err = EncodeMap(m)
+		vs, err = EncodeValues(m)
 		if err != nil {
 			return nil, err
 		}
@@ -66,9 +66,9 @@ func (c codec) Unmarshal(data []byte, v interface{}) error {
 		rv = rv.Elem()
 	}
 	if m, ok := v.(proto.Message); ok {
-		return MapProto(m, vs)
+		return DecodeValues(m, vs)
 	} else if m, ok := reflect.Indirect(reflect.ValueOf(v)).Interface().(proto.Message); ok {
-		return MapProto(m, vs)
+		return DecodeValues(m, vs)
 	}
 
 	return c.decoder.Decode(v, vs)

encoding/form/proto_decode.go

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
+	"net/url"
 	"strconv"
 	"strings"
 	"time"
@@ -19,7 +20,8 @@ import (
 	"google.golang.org/protobuf/types/known/wrapperspb"
 )
 
-func MapProto(msg proto.Message, values map[string][]string) error {
+// DecodeValues decode url value into proto message.
+func DecodeValues(msg proto.Message, values url.Values) error {
 	for key, values := range values {
 		if err := populateFieldValues(msg.ProtoReflect(), strings.Split(key, "."), values); err != nil {
 			return err
@@ -285,7 +287,9 @@ func parseMessage(md protoreflect.MessageDescriptor, value string) (protoreflect
 		msg = wrapperspb.Bytes(v)
 	case "google.protobuf.FieldMask":
 		fm := &field_mask.FieldMask{}
-		fm.Paths = append(fm.Paths, strings.Split(value, ",")...)
+		for _, fv := range strings.Split(value, ",") {
+			fm.Paths = append(fm.Paths, jsonSnakeCase(fv))
+		}
 		msg = fm
 	case "google.protobuf.Value":
 		fm, err := structpb.NewValue(value)
@@ -298,3 +302,23 @@ func parseMessage(md protoreflect.MessageDescriptor, value string) (protoreflect
 	}
 	return protoreflect.ValueOfMessage(msg.ProtoReflect()), nil
 }
+
+// jsonSnakeCase converts a camelCase identifier to a snake_case identifier,
+// according to the protobuf JSON specification.
+// references: https://github.com/protocolbuffers/protobuf-go/blob/master/encoding/protojson/well_known_types.go#L864
+func jsonSnakeCase(s string) string {
+	var b []byte
+	for i := 0; i < len(s); i++ { // proto identifiers are always ASCII
+		c := s[i]
+		if isASCIIUpper(c) {
+			b = append(b, '_')
+			c += 'a' - 'A' // convert to lowercase
+		}
+		b = append(b, c)
+	}
+	return string(b)
+}
+
+func isASCIIUpper(c byte) bool {
+	return 'A' <= c && c <= 'Z'
+}

encoding/form/proto_encode.go

@@ -13,8 +13,8 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
-// EncodeMap encode proto message to url query.
+// EncodeValues encode a message into url values.
-func EncodeMap(msg proto.Message) (url.Values, error) {
+func EncodeValues(msg proto.Message) (url.Values, error) {
 	if msg == nil || (reflect.ValueOf(msg).Kind() == reflect.Ptr && reflect.ValueOf(msg).IsNil()) {
 		return url.Values{}, nil
 	}
@@ -165,8 +165,34 @@ func encodeMessage(msgDescriptor protoreflect.MessageDescriptor, value protorefl
 		if !ok {
 			return "", nil
 		}
+		for i, v := range m.Paths {
+			m.Paths[i] = jsonCamelCase(v)
+		}
 		return strings.Join(m.Paths, ","), nil
 	default:
 		return "", fmt.Errorf("unsupported message type: %q", string(msgDescriptor.FullName()))
 	}
 }
+
+// JSONCamelCase converts a snake_case identifier to a camelCase identifier,
+// according to the protobuf JSON specification.
+// references: https://github.com/protocolbuffers/protobuf-go/blob/master/encoding/protojson/well_known_types.go#L842
+func jsonCamelCase(s string) string {
+	var b []byte
+	var wasUnderscore bool
+	for i := 0; i < len(s); i++ { // proto identifiers are always ASCII
+		c := s[i]
+		if c != '_' {
+			if wasUnderscore && isASCIILower(c) {
+				c -= 'a' - 'A' // convert to uppercase
+			}
+			b = append(b, c)
+		}
+		wasUnderscore = c == '_'
+	}
+	return string(b)
+}
+
+func isASCIILower(c byte) bool {
+	return 'a' <= c && c <= 'z'
+}

transport/http/binding/encode.go

@@ -35,7 +35,7 @@ func EncodeURL(pathTemplate string, msg proto.Message, needQuery bool) string {
 		return in
 	})
 	if needQuery {
-		u, err := form.EncodeMap(msg)
+		u, err := form.EncodeValues(msg)
 		if err == nil && len(u) > 0 {
 			for key := range pathParams {
 				delete(u, key)