API Resource

gistfile1.go

package main

import (
	"encoding/json"
	"os"
	"time"
)

// Timestamp wraps time.Time and implements the json.Marshaller interface
// for presenting a timestamp in ISO8601 format.
type Timestamp struct {
	time.Time
}

// MarshalJSON implements the json.Marshaller interface.
func (t Timestamp) MarshalJSON() ([]byte, error) {
	return []byte(`"` + t.ISO8601() + `"`), nil
}

// ISO8601 returns an ISO8601 (RFC3339) formatted string in UTC.
func (t Timestamp) ISO8601() string {
	return t.UTC().Format(time.RFC3339)
}

// Resource as an interface that provides a means of transforming a domain
// model into an API resource suitable for encoding.
type Resource interface {
	Present() interface{}
}

// jobs is our domain model, probably in a separate package.
type job struct {
	ID        int
	CreatedAt time.Time
}

// JobResource is an implementation of the Resource interface.
type JobResource struct {
	*job
}

// Present implements the Resource interface.
func (r *JobResource) Present() interface{} {
	return struct {
		ID        int       `json:"id"`
		CreatedAt Timestamp `json:"created_at"`
	}{
		ID:        r.job.ID,
		CreatedAt: Timestamp{Time: r.job.CreatedAt},
	}
}

func main() {
	j := &job{ID: 1, CreatedAt: time.Now()}
	r := &JobResource{j}

	json.NewEncoder(os.Stdout).Encode(r.Present())
	// {"id":1,"created_at":"2014-07-17T15:08:16Z"}
}