package runtime import ( "bytes" "encoding/json" "fmt" "io" "reflect" "github.com/golang/protobuf/jsonpb" "github.com/golang/protobuf/proto" ) // JSONPb is a Marshaler which marshals/unmarshals into/from JSON // with the "github.com/golang/protobuf/jsonpb". // It supports fully functionality of protobuf unlike JSONBuiltin. // // The NewDecoder method returns a DecoderWrapper, so the underlying // *json.Decoder methods can be used. type JSONPb jsonpb.Marshaler // ContentType always returns "application/json". func (*JSONPb) ContentType() string { return "application/json" } // Marshal marshals "v" into JSON. func (j *JSONPb) Marshal(v interface{}) ([]byte, error) { if _, ok := v.(proto.Message); !ok { return j.marshalNonProtoField(v) } var buf bytes.Buffer if err := j.marshalTo(&buf, v); err != nil { return nil, err } return buf.Bytes(), nil } func (j *JSONPb) marshalTo(w io.Writer, v interface{}) error { p, ok := v.(proto.Message) if !ok { buf, err := j.marshalNonProtoField(v) if err != nil { return err } _, err = w.Write(buf) return err } return (*jsonpb.Marshaler)(j).Marshal(w, p) } var ( // protoMessageType is stored to prevent constant lookup of the same type at runtime. protoMessageType = reflect.TypeOf((*proto.Message)(nil)).Elem() ) // marshalNonProto marshals a non-message field of a protobuf message. // This function does not correctly marshals arbitrary data structure into JSON, // but it is only capable of marshaling non-message field values of protobuf, // i.e. primitive types, enums; pointers to primitives or enums; maps from // integer/string types to primitives/enums/pointers to messages. func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) { if v == nil { return []byte("null"), nil } rv := reflect.ValueOf(v) for rv.Kind() == reflect.Ptr { if rv.IsNil() { return []byte("null"), nil } rv = rv.Elem() } if rv.Kind() == reflect.Slice { if rv.IsNil() { if j.EmitDefaults { return []byte("[]"), nil } return []byte("null"), nil } if rv.Type().Elem().Implements(protoMessageType) { var buf bytes.Buffer err := buf.WriteByte('[') if err != nil { return nil, err } for i := 0; i < rv.Len(); i++ { if i != 0 { err = buf.WriteByte(',') if err != nil { return nil, err } } if err = (*jsonpb.Marshaler)(j).Marshal(&buf, rv.Index(i).Interface().(proto.Message)); err != nil { return nil, err } } err = buf.WriteByte(']') if err != nil { return nil, err } return buf.Bytes(), nil } } if rv.Kind() == reflect.Map { m := make(map[string]*json.RawMessage) for _, k := range rv.MapKeys() { buf, err := j.Marshal(rv.MapIndex(k).Interface()) if err != nil { return nil, err } m[fmt.Sprintf("%v", k.Interface())] = (*json.RawMessage)(&buf) } if j.Indent != "" { return json.MarshalIndent(m, "", j.Indent) } return json.Marshal(m) } if enum, ok := rv.Interface().(protoEnum); ok && !j.EnumsAsInts { return json.Marshal(enum.String()) } return json.Marshal(rv.Interface()) } // Unmarshal unmarshals JSON "data" into "v" func (j *JSONPb) Unmarshal(data []byte, v interface{}) error { return unmarshalJSONPb(data, v) } // NewDecoder returns a Decoder which reads JSON stream from "r". func (j *JSONPb) NewDecoder(r io.Reader) Decoder { d := json.NewDecoder(r) return DecoderWrapper{Decoder: d} } // DecoderWrapper is a wrapper around a *json.Decoder that adds // support for protos to the Decode method. type DecoderWrapper struct { *json.Decoder } // Decode wraps the embedded decoder's Decode method to support // protos using a jsonpb.Unmarshaler. func (d DecoderWrapper) Decode(v interface{}) error { return decodeJSONPb(d.Decoder, v) } // NewEncoder returns an Encoder which writes JSON stream into "w". func (j *JSONPb) NewEncoder(w io.Writer) Encoder { return EncoderFunc(func(v interface{}) error { if err := j.marshalTo(w, v); err != nil { return err } // mimic json.Encoder by adding a newline (makes output // easier to read when it contains multiple encoded items) _, err := w.Write(j.Delimiter()) return err }) } func unmarshalJSONPb(data []byte, v interface{}) error { d := json.NewDecoder(bytes.NewReader(data)) return decodeJSONPb(d, v) } func decodeJSONPb(d *json.Decoder, v interface{}) error { p, ok := v.(proto.Message) if !ok { return decodeNonProtoField(d, v) } unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields} return unmarshaler.UnmarshalNext(d, p) } func decodeNonProtoField(d *json.Decoder, v interface{}) error { rv := reflect.ValueOf(v) if rv.Kind() != reflect.Ptr { return fmt.Errorf("%T is not a pointer", v) } for rv.Kind() == reflect.Ptr { if rv.IsNil() { rv.Set(reflect.New(rv.Type().Elem())) } if rv.Type().ConvertibleTo(typeProtoMessage) { unmarshaler := &jsonpb.Unmarshaler{AllowUnknownFields: allowUnknownFields} return unmarshaler.UnmarshalNext(d, rv.Interface().(proto.Message)) } rv = rv.Elem() } if rv.Kind() == reflect.Map { if rv.IsNil() { rv.Set(reflect.MakeMap(rv.Type())) } conv, ok := convFromType[rv.Type().Key().Kind()] if !ok { return fmt.Errorf("unsupported type of map field key: %v", rv.Type().Key()) } m := make(map[string]*json.RawMessage) if err := d.Decode(&m); err != nil { return err } for k, v := range m { result := conv.Call([]reflect.Value{reflect.ValueOf(k)}) if err := result[1].Interface(); err != nil { return err.(error) } bk := result[0] bv := reflect.New(rv.Type().Elem()) if err := unmarshalJSONPb([]byte(*v), bv.Interface()); err != nil { return err } rv.SetMapIndex(bk, bv.Elem()) } return nil } if _, ok := rv.Interface().(protoEnum); ok { var repr interface{} if err := d.Decode(&repr); err != nil { return err } switch repr.(type) { case string: // TODO(yugui) Should use proto.StructProperties? return fmt.Errorf("unmarshaling of symbolic enum %q not supported: %T", repr, rv.Interface()) case float64: rv.Set(reflect.ValueOf(int32(repr.(float64))).Convert(rv.Type())) return nil default: return fmt.Errorf("cannot assign %#v into Go type %T", repr, rv.Interface()) } } return d.Decode(v) } type protoEnum interface { fmt.Stringer EnumDescriptor() ([]byte, []int) } var typeProtoMessage = reflect.TypeOf((*proto.Message)(nil)).Elem() // Delimiter for newline encoded JSON streams. func (j *JSONPb) Delimiter() []byte { return []byte("\n") } // allowUnknownFields helps not to return an error when the destination // is a struct and the input contains object keys which do not match any // non-ignored, exported fields in the destination. var allowUnknownFields = true // DisallowUnknownFields enables option in decoder (unmarshaller) to // return an error when it finds an unknown field. This function must be // called before using the JSON marshaller. func DisallowUnknownFields() { allowUnknownFields = false }