media

Overview ¶

Package media normalizes encoding and decoding by providing a registry of encoders and decoders for MIME types.

Create applications supporting multiple encoding types by importing this media package and specific encoding packages to register their encoders and decoders with a MIME type. Once registered, encoders/decoders can be pulled from the registry by providing a MIME type.

The following partial example demonstrates how to create a net/http Handler capable of returning a response whose body is encoded as either JSON or Protocol Buffers depending on the HTTP request's "Accept" header.

import (
  "net/http"

  "github.com/go-goo/encoding/media"
  _ "github.com/go-goo/encoding/media/json"
  _ "github.com/go-goo/encoding/media/proto"
)

// valid protobuf message
type Thing struct {
  Text string `protobuf:"bytes,1,opt,name=text,proto3" json:"text,omitempty"`
}

func Handler(w http.ResponseWriter, r *http.Request) {
  enc, err := media.NewEncoder(r.Header.Get("Accept"), w)
  if err != nil {
    http.Error(w, err.Error(), http.StatusNotImplemented)
    return
  }
  if err := enc.Encode(&Thing{"hello media"}); err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
  }
}

Creating and registering new encodings is accomplished by defining encoders and/or decoders, and calling Register in an init function passing an EncoderFunc and DecoderFunc.

// text/go encoder
func init() {
  media.Register("text/go", newEncoder, nil)
}

func newEncoder(w io.Writer) (media.Encoder, error) {
  return &encoder{w}
}

type encoder struct {
  w io.Writer
}

func (a *encoder) Encode(v interface{}) error {
  _, err = a.w.Write([]byte(fmt.Sprintf("%#v", v)))
  return err
}