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@nmerouze
Created December 5, 2014 12:07
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JSON-API with Go and MongoDB: Part 2
package main
import (
"encoding/json"
"log"
"net/http"
"reflect"
"time"
"github.com/gorilla/context"
"github.com/julienschmidt/httprouter"
"github.com/justinas/alice"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
// Errors
type Errors struct {
Errors []*Error `json:"errors"`
}
type Error struct {
Id string `json:"id"`
Status int `json:"status"`
Title string `json:"title"`
Detail string `json:"detail"`
}
var (
ErrNotAcceptable = &Error{"not_acceptable", 406, "Not Acceptable", "Accept header must be set to 'application/vnd.api+json'."}
ErrInternalServer = &Error{"internal_server_error", 500, "Internal Server Error", "Something went wrong."}
)
func WriteError(w http.ResponseWriter, err *Error) {
w.Header().Set("Content-Type", "application/vnd.api+json")
w.WriteHeader(err.Status)
json.NewEncoder(w).Encode(Errors{[]*Error{err}})
}
// Repo
type Tea struct {
Id bson.ObjectId `json:"id,omitempty" bson:"_id,omitempty"`
Name string `json:"name"`
Category string `json:"category"`
}
type TeaResource struct {
Data Tea `json:"data"`
}
type TeaRepo struct {
coll *mgo.Collection
}
func (r *TeaRepo) Find(id string) (TeaResource, error) {
result := TeaResource{}
err := r.coll.FindId(bson.ObjectIdHex(id)).One(&result.Data)
if err != nil {
return result, err
}
return result, nil
}
type appContext struct {
db *mgo.Database
}
func (c *appContext) teaHandler(w http.ResponseWriter, r *http.Request) {
params := context.Get(r, "params").(httprouter.Params)
repo := TeaRepo{c.db.C("teas")}
tea, err := repo.Find(params.ByName("id"))
if err != nil {
panic(err)
}
w.Header().Set("Content-Type", "application/vnd.api+json")
json.NewEncoder(w).Encode(tea)
}
func recoverHandler(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
defer func() {
if err := recover(); err != nil {
log.Printf("panic: %+v", err)
WriteError(w, ErrInternalServer)
}
}()
next.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
func loggingHandler(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
t1 := time.Now()
next.ServeHTTP(w, r)
t2 := time.Now()
log.Printf("[%s] %q %v\n", r.Method, r.URL.String(), t2.Sub(t1))
}
return http.HandlerFunc(fn)
}
func acceptHandler(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
if r.Header.Get("Accept") != "application/vnd.api+json" {
WriteError(w, ErrNotAcceptable)
return
}
next.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
type router struct {
*httprouter.Router
}
func (r *router) Get(path string, handler http.Handler) {
r.GET(path, wrapHandler(handler))
}
func NewRouter() *router {
return &router{httprouter.New()}
}
func wrapHandler(h http.Handler) httprouter.Handle {
return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
context.Set(r, "params", ps)
h.ServeHTTP(w, r)
}
}
func main() {
session, err := mgo.Dial("localhost")
if err != nil {
panic(err)
}
defer session.Close()
session.SetMode(mgo.Monotonic, true)
appC := appContext{session.DB("test")}
commonHandlers := alice.New(context.ClearHandler, loggingHandler, recoverHandler, acceptHandler)
router := NewRouter()
router.Get("/teas/:id", commonHandlers.ThenFunc(appC.teaHandler))
http.ListenAndServe(":8080", router)
}
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