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jsonpb_marshal.go
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/
jsonpb_marshal.go
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// Copyright 2016 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Tamir Duberstein (tamird@gmail.com)
package util
import (
"bytes"
"encoding/json"
"fmt"
"io"
"reflect"
"github.com/gogo/protobuf/jsonpb"
"github.com/gogo/protobuf/proto"
gwruntime "github.com/grpc-ecosystem/grpc-gateway/runtime"
"github.com/pkg/errors"
)
var _ gwruntime.Marshaler = (*JSONPb)(nil)
var typeProtoMessage = reflect.TypeOf((*proto.Message)(nil)).Elem()
// JSONPb is a gwruntime.Marshaler that uses github.com/gogo/protobuf/jsonpb.
type JSONPb jsonpb.Marshaler
// ContentType implements gwruntime.Marshaler.
func (*JSONPb) ContentType() string {
return "application/json"
}
// Marshal implements gwruntime.Marshaler.
func (j *JSONPb) Marshal(v interface{}) ([]byte, error) {
return j.marshal(v)
}
// a lower-case version of marshal to allow for a call from
// marshalNonProtoField without upsetting TestProtoMarshal().
func (j *JSONPb) marshal(v interface{}) ([]byte, error) {
if pb, ok := v.(proto.Message); ok {
var buf bytes.Buffer
marshalFn := (*jsonpb.Marshaler)(j).Marshal
if err := marshalFn(&buf, pb); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
return j.marshalNonProtoField(v)
}
// Cribbed verbatim from grpc-gateway.
type protoEnum interface {
fmt.Stringer
EnumDescriptor() ([]byte, []int)
}
// Cribbed verbatim from grpc-gateway.
func (j *JSONPb) marshalNonProtoField(v interface{}) ([]byte, error) {
rv := reflect.ValueOf(v)
for rv.Kind() == reflect.Ptr {
if rv.IsNil() {
return []byte("null"), nil
}
rv = rv.Elem()
}
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 implements gwruntime.Marshaler.
func (j *JSONPb) Unmarshal(data []byte, v interface{}) error {
if pb, ok := v.(proto.Message); ok {
return jsonpb.Unmarshal(bytes.NewReader(data), pb)
}
return errors.Errorf("unexpected type %T does not implement %s", v, typeProtoMessage)
}
// NewDecoder implements gwruntime.Marshaler.
func (j *JSONPb) NewDecoder(r io.Reader) gwruntime.Decoder {
return gwruntime.DecoderFunc(func(v interface{}) error {
if pb, ok := v.(proto.Message); ok {
return jsonpb.Unmarshal(r, pb)
}
return errors.Errorf("unexpected type %T does not implement %s", v, typeProtoMessage)
})
}
// NewEncoder implements gwruntime.Marshaler.
func (j *JSONPb) NewEncoder(w io.Writer) gwruntime.Encoder {
return gwruntime.EncoderFunc(func(v interface{}) error {
if pb, ok := v.(proto.Message); ok {
marshalFn := (*jsonpb.Marshaler)(j).Marshal
return marshalFn(w, pb)
}
return errors.Errorf("unexpected type %T does not implement %s", v, typeProtoMessage)
})
}