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Encoding

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 in encoding

These formats are battery-included.

  • form
  • json
  • protobuf
  • xml
  • yaml

Interface

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

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

Example of Codec Implementation

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

// https://github.com/go-kratos/kratos/blob/main/encoding/json/json.go
package json

import (
"encoding/json"
"reflect"

"github.com/go-kratos/kratos/v2/encoding"
"google.golang.org/protobuf/encoding/protojson"
"google.golang.org/protobuf/proto"
)

// Name is the name registered for the json codec.
const Name = "json"

var (
// MarshalOptions is a configurable JSON format marshaller.
MarshalOptions = protojson.MarshalOptions{
EmitUnpopulated: true,
}
// UnmarshalOptions is a configurable JSON format parser.
UnmarshalOptions = protojson.UnmarshalOptions{
DiscardUnknown: true,
}
)

func init() {
encoding.RegisterCodec(codec{})
}

// codec is a Codec implementation with json.
type codec struct{}

func (codec) Marshal(v interface{}) ([]byte, error) {
switch m := v.(type) {
case json.Marshaler:
return m.MarshalJSON()
case proto.Message:
return MarshalOptions.Marshal(m)
default:
return json.Marshal(m)
}
}

func (codec) Unmarshal(data []byte, v interface{}) error {
switch m := v.(type) {
case json.Unmarshaler:
return m.UnmarshalJSON(data)
case proto.Message:
return UnmarshalOptions.Unmarshal(data, m)
default:
rv := reflect.ValueOf(v)
for rv := rv; rv.Kind() == reflect.Ptr; {
if rv.IsNil() {
rv.Set(reflect.New(rv.Type().Elem()))
}
rv = rv.Elem()
}
if m, ok := reflect.Indirect(rv).Interface().(proto.Message); ok {
return UnmarshalOptions.Unmarshal(data, m)
}
return json.Unmarshal(data, m)
}
}

func (codec) Name() string {
return Name
}

Usage

Register Custom Codec

encoding.RegisterCodec(codec{})

Get the Codec

jsonCodec := encoding.GetCodec("json")

Serialization

// You should manually import this package if you use it directly: import _ "github.com/go-kratos/kratos/v2/encoding/json"
jsonCodec := encoding.GetCodec("json")
type user struct {
Name string
Age string
state bool
}
u := &user{
Name: "kratos",
Age: "2",
state: false,
}
bytes, _ := jsonCodec.Marshal(u)
fmt.Println(string(bytes))
// output {"Name":"kratos","Age":"2"}

Deserialization

// You should manually import this package if you use it directly:import _ "github.com/go-kratos/kratos/v2/encoding/json"
jsonCodec := encoding.GetCodec("json")
type user struct {
Name string
Age string
state bool
}
u := &user{}
jsonCodec.Unmarshal([]byte(`{"Name":"kratos","Age":"2"}`), &u)
fmt.Println(*u)
//output &{kratos 2 false}