## 类似 Twitter 的 API 服务
这个示例演示如何使用 MongoDB，JWT 和 JSON 创建一个类似 Twitter 的 REST API 服务。
#### 模型
`user.go`
```go
package model
import "gopkg.in/mgo.v2/bson"
type (
User struct {
ID bson.ObjectId `json:"id" bson:"_id,omitempty"`
Email string `json:"email" bson:"email"`
Password string `json:"password,omitempty" bson:"password"`
Token string `json:"token,omitempty" bson:"-"`
Followers []string `json:"followers,omitempty" bson:"followers,omitempty"`
}
)
```
`post.go`
```go
package model
import "gopkg.in/mgo.v2/bson"
type (
Post struct {
ID bson.ObjectId `json:"id" bson:"_id,omitempty"`
To string `json:"to" bson:"to"`
From string `json:"from" bson:"from"`
Message string `json:"message" bson:"message"`
}
)
```
### 控制器
`handler.go`
```go
package handler
import mgo "gopkg.in/mgo.v2"
type (
Handler struct {
DB *mgo.Session
}
)
const (
// Key (Should come from somewhere else).
Key = "secret"
)
```
`user.go`
```go
package handler
import (
"net/http"
"time"
jwt "github.com/dgrijalva/jwt-go"
"github.com/labstack/echo"
"github.com/labstack/echo/cookbook/twitter/model"
mgo "gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
func (h *Handler) Signup(c echo.Context) (err error) {
// Bind
u := &model.User{ID: bson.NewObjectId()}
if err = c.Bind(u); err != nil {
return
}
// Validate
if u.Email == "" || u.Password == "" {
return &echo.HTTPError{Code: http.StatusBadRequest, Message: "invalid email or password"}
}
// Save user
db := h.DB.Clone()
defer db.Close()
if err = db.DB("twitter").C("users").Insert(u); err != nil {
return
}
return c.JSON(http.StatusCreated, u)
}
func (h *Handler) Login(c echo.Context) (err error) {
// Bind
u := new(model.User)
if err = c.Bind(u); err != nil {
return
}
// Find user
db := h.DB.Clone()
defer db.Close()
if err = db.DB("twitter").C("users").
Find(bson.M{"email": u.Email, "password": u.Password}).One(u); err != nil {
if err == mgo.ErrNotFound {
return &echo.HTTPError{Code: http.StatusUnauthorized, Message: "invalid email or password"}
}
return
}
//-----
// JWT
//-----
// Create token
token := jwt.New(jwt.SigningMethodHS256)
// Set claims
claims := token.Claims.(jwt.MapClaims)
claims["id"] = u.ID
claims["exp"] = time.Now().Add(time.Hour * 72).Unix()
// Generate encoded token and send it as response
u.Token, err = token.SignedString([]byte(Key))
if err != nil {
return err
}
u.Password = "" // Don't send password
return c.JSON(http.StatusOK, u)
}
func (h *Handler) Follow(c echo.Context) (err error) {
userID := userIDFromToken(c)
id := c.Param("id")
// Add a follower to user
db := h.DB.Clone()
defer db.Close()
if err = db.DB("twitter").C("users").
UpdateId(bson.ObjectIdHex(id), bson.M{"$addToSet": bson.M{"followers": userID}}); err != nil {
if err == mgo.ErrNotFound {
return echo.ErrNotFound
}
}
return
}
func userIDFromToken(c echo.Context) string {
user := c.Get("user").(*jwt.Token)
claims := user.Claims.(jwt.MapClaims)
return claims["id"].(string)
}
```
`post.go`
```go
package handler
import (
"net/http"
"strconv"
"github.com/labstack/echo"
"github.com/labstack/echo/cookbook/twitter/model"
mgo "gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
func (h *Handler) CreatePost(c echo.Context) (err error) {
u := &model.User{
ID: bson.ObjectIdHex(userIDFromToken(c)),
}
p := &model.Post{
ID: bson.NewObjectId(),
From: u.ID.Hex(),
}
if err = c.Bind(p); err != nil {
return
}
// Validation
if p.To == "" || p.Message == "" {
return &echo.HTTPError{Code: http.StatusBadRequest, Message: "invalid to or message fields"}
}
// Find user from database
db := h.DB.Clone()
defer db.Close()
if err = db.DB("twitter").C("users").FindId(u.ID).One(u); err != nil {
if err == mgo.ErrNotFound {
return echo.ErrNotFound
}
return
}
// Save post in database
if err = db.DB("twitter").C("posts").Insert(p); err != nil {
return
}
return c.JSON(http.StatusCreated, p)
}
func (h *Handler) FetchPost(c echo.Context) (err error) {
userID := userIDFromToken(c)
page, _ := strconv.Atoi(c.QueryParam("page"))
limit, _ := strconv.Atoi(c.QueryParam("limit"))
// Defaults
if page == 0 {
page = 1
}
if limit == 0 {
limit = 100
}
// Retrieve posts from database
posts := []*model.Post{}
db := h.DB.Clone()
if err = db.DB("twitter").C("posts").
Find(bson.M{"to": userID}).
Skip((page - 1) * limit).
Limit(limit).
All(&posts); err != nil {
return
}
defer db.Close()
return c.JSON(http.StatusOK, posts)
}
```
### API
#### 注册
*用户注册*
- 用请求里取出用户信息验证合法性。
- 不合法的邮箱和密码，返回 `400 - Bad Request`。
- 合法的邮箱和密码，保存数据到数据库并返回 `201 - Created`。
**请求**
```shell
curl \
-X POST \
http://localhost:1323/signup \
-H "Content-Type: application/json" \
-d '{"email":"jon@labstack.com","password":"shhh!"}'
```
**响应**
`201 - Created`
```go
{
"id": "58465b4ea6fe886d3215c6df",
"email": "jon@labstack.com",
"password": "shhh!"
}
```
### Login
User login
- Retrieve user credentials from the body and validate against database.
- For invalid credentials, send `401 - Unauthorized` response.
- For valid credentials, send `200 - OK` response:
- Generate JWT for the user and send it as response.
- Each subsequent request must include JWT in the `Authorization` header.
Method: `POST`<br>
Path: `/login`
#### Request
```sh
curl \
-X POST \
http://localhost:1323/login \
-H "Content-Type: application/json" \
-d '{"email":"jon@labstack.com","password":"shhh!"}'
```
#### Response
`200 - OK`
```js
{
"id": "58465b4ea6fe886d3215c6df",
"email": "jon@labstack.com",
"token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0ODEyNjUxMjgsImlkIjoiNTg0NjViNGVhNmZlODg2ZDMyMTVjNmRmIn0.1IsGGxko1qMCsKkJDQ1NfmrZ945XVC9uZpcvDnKwpL0"
}
```
Client should store the token, for browsers, you may use local storage.
### Follow
Follow a user
- For invalid token, send `400 - Bad Request` response.
- For valid token:
- If user is not found, send `404 - Not Found` response.
- Add a follower to the specified user in the path parameter and send `200 - OK` response.
Method: `POST` <br>
Path: `/follow/:id`
#### Request
```sh
curl \
-X POST \
http://localhost:1323/follow/58465b4ea6fe886d3215c6df \
-H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0ODEyNjUxMjgsImlkIjoiNTg0NjViNGVhNmZlODg2ZDMyMTVjNmRmIn0.1IsGGxko1qMCsKkJDQ1NfmrZ945XVC9uZpcvDnKwpL0"
```
#### Response
`200 - OK`
### Post
Post a message to specified user
- For invalid request payload, send `400 - Bad Request` response.
- If user is not found, send `404 - Not Found` response.
- Otherwise save post in the database and return it via `201 - Created` response.
Method: `POST` <br>
Path: `/posts`
#### Request
```sh
curl \
-X POST \
http://localhost:1323/posts \
-H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0ODEyNjUxMjgsImlkIjoiNTg0NjViNGVhNmZlODg2ZDMyMTVjNmRmIn0.1IsGGxko1qMCsKkJDQ1NfmrZ945XVC9uZpcvDnKwpL0" \
-H "Content-Type: application/json" \
-d '{"to":"58465b4ea6fe886d3215c6df","message":"hello"}'
```
#### Response
`201 - Created`
```js
{
"id": "584661b9a6fe8871a3804cba",
"to": "58465b4ea6fe886d3215c6df",
"from": "58465b4ea6fe886d3215c6df",
"message": "hello"
}
```
### Feed
List most recent messages based on optional `page` and `limit` query parameters
Method: `GET` <br>
Path: `/feed?page=1&limit=5`
#### Request
```sh
curl \
-X GET \
http://localhost:1323/feed \
-H "Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0ODEyNjUxMjgsImlkIjoiNTg0NjViNGVhNmZlODg2ZDMyMTVjNmRmIn0.1IsGGxko1qMCsKkJDQ1NfmrZ945XVC9uZpcvDnKwpL0"
```
#### Response
`200 - OK`
```js
[
{
"id": "584661b9a6fe8871a3804cba",
"to": "58465b4ea6fe886d3215c6df",
"from": "58465b4ea6fe886d3215c6df",
"message": "hello"
}
]
```
