We’ve abstracted the Codec interface to unify the serialization/deserialization logic for processing requests, and you can implement your own Codec to support more formats. The specific source code is inencoding。

These formats are battery-included.

  • json
  • protobuf
  • xml
  • yaml

Interface

You should implement the following Codec interface for your custom codec.

  1. // Codec interface is for serialization and deserialization, notice that these methods must be thread-safe.
  2. type Codec interface {
  3.     Marshal(v interface{}) ([]byte, error)
  4.     Unmarshal(data []byte, v interface{}) error
  5.     Name() string
  6. }

Example of Codec Implementation

You may refer to the included implementations in kratos, such as json when you implementing custom Codec.

  1. // https://github.com/go-kratos/kratos/blob/main/encoding/json/json.go
  2. package json
  4. import (
  5.     "encoding/json"
  6.     "reflect"
  8.     "github.com/go-kratos/kratos/v2/encoding"
  9.     "google.golang.org/protobuf/encoding/protojson"
  10.     "google.golang.org/protobuf/proto"
  11. )
  13. // Name is the name registered for the json codec.
  14. const Name = "json"
  16. var (
  17.     // MarshalOptions is a configurable JSON format marshaller.
  18.     MarshalOptions = protojson.MarshalOptions{
  19.         EmitUnpopulated: true,
  20.     }
  21.     // UnmarshalOptions is a configurable JSON format parser.
  22.     UnmarshalOptions = protojson.UnmarshalOptions{
  23.         DiscardUnknown: true,
  24.     }
  25. )
  27. func init() {
  28.     encoding.RegisterCodec(codec{})
  29. }
  31. // codec is a Codec implementation with json.
  32. type codec struct{}
  34. func (codec) Marshal(v interface{}) ([]byte, error) {
  35.     if m, ok := v.(proto.Message); ok {
  36.         return MarshalOptions.Marshal(m)
  37.     }
  38.     return json.Marshal(v)
  39. }
  41. func (codec) Unmarshal(data []byte, v interface{}) error {
  42.     rv := reflect.ValueOf(v)
  43.     for rv.Kind() == reflect.Ptr {
  44.         if rv.IsNil() {
  45.             rv.Set(reflect.New(rv.Type().Elem()))
  46.         }
  47.         rv = rv.Elem()
  48.     }
  49.     if m, ok := v.(proto.Message); ok {
  50.         return UnmarshalOptions.Unmarshal(data, m)
  51.     } else if m, ok := reflect.Indirect(reflect.ValueOf(v)).Interface().(proto.Message); ok {
  52.         return UnmarshalOptions.Unmarshal(data, m)
  53.     }
  54.     return json.Unmarshal(data, v)
  55. }
  57. func (codec) Name() string {
  58.     return Name
  59. }

Usage

Register Custom Codec

  1. encoding.RegisterCodec(codec{})

Get the Codec

  1. jsonCodec := encoding.GetCodec("json")

Serialization

  1. // You should manually import this package if you use it directly: import _ "github.com/go-kratos/kratos/v2/encoding/json"
  2. jsonCode := encoding.GetCodec("json")
  3. type user struct {
  4.     Name string
  5.     Age string
  6.     state bool
  7. }
  8. u := &user{
  9.     Name:  "kratos",
  10.     Age:   "2",
  11.     state: false,
  12. }
  13. bytes, _ := jsonCode.Marshal(u)
  14. // output {"Name":"kratos","Age":"2"}

Deserialization

  1. // You should manually import this package if you use it directly:import _ "github.com/go-kratos/kratos/v2/encoding/json"
  2. jsonCode := encoding.GetCodec("json")
  3. type user struct {
  4.     Name string
  5.     Age string
  6.     state bool
  7. }
  8. u := &user{}
  9. jsonCode.Unmarshal([]byte(`{"Name":"kratos","Age":"2"}`), &u)
  10. //output &{kratos 2 false}