Encoding

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}