Gin Web Framework

brief introduction

• web framework developed based on httprouter: https://github.com/gin-gonic/gin
• Provides Martini style API, but 40 times faster than Martini
• Very lightweight, simple to use

Installation and use of Gin framework

• Install: go get -u github.com/gin-gonic/gin

  Basic use

import "github.com/gin-gonic/gin"

func main() {
   r := gin.Default()
   r.GET("/ping", func(c *gin.Context) {
      c.JSON(200, gin.H{
         "message": "pong",
      })
   })
   r.Run("0.0.0.0:9090")
}

restful API support

• Abstract the designed API into resources and identify them with URI s
• For each resource, use a unified method to operate
• Unified methods: GET,POST, PUT, DELETE

import (
   "github.com/gin-gonic/gin"
   "net/http"
)

type Result struct {
   Message string   `json:"message"`
   Code    int      `json:"code"`
}

func handleUserInfo(c *gin.Context) {
   var result Result = Result{
      Message: "hello",
      Code:    0,
   }
   c.JSON(http.StatusOK,result)
}

func main() {
   r := gin.Default()
   r.GET("/user/info", handleUserInfo)
   r.Run("0.0.0.0:9090")
}

queryString design

• Query class: http://127.0.0.1:9090/user/info?username=dadasd&&passwd=1234
• Routing class: http://127.0.0.1:9090/user/info/2020/12

import (
   "github.com/gin-gonic/gin"
   "net/http"
)

type Result struct {
   Message string   `json:"message"`
   Code    int      `json:"code"`
}

type UserInfo struct {
   Result
   UserName  string   `json:"username"`
   Passwd string      `json:"passwd"`
}

func handleUserParams(c *gin.Context) {
   //Query class interface
   username := c.Query("username")
   passwd := c.DefaultQuery("passwd","adcdefg")

   var result UserInfo = UserInfo{
      Result{
         Message: "success",
         Code:    200,
      },
      username,
      passwd,
   }
   c.JSON(http.StatusOK,result)
}

func handleUserInfo(c *gin.Context) {
   //Routing interface
   username := c.Param("username")
   passwd := c.Param("passwd")

   var result UserInfo = UserInfo{
      Result{
         Message: "success",
         Code:    200,
      },
      username,
      passwd,
   }
   c.JSON(http.StatusOK,result)
}

func main() {
   r := gin.Default()
   r.GET("/user/info", handleUserParams)
   r.GET("/user/info/:username/:passwd", handleUserInfo)
   r.Run("0.0.0.0:9090")
}

Gin framework parameter passing

Get form parameters

import (
   "github.com/gin-gonic/gin"
   "net/http"
)

type Result struct {
   Message string   `json:"message"`
   Code    int      `json:"code"`
}

type UserInfo struct {
   Result
   UserName  string   `json:"username"`
   Passwd string      `json:"passwd"`
}

func handleUserInfo(c *gin.Context) {
   username := c.PostForm("username")
   passwd := c.PostForm("passwd")

   var result UserInfo = UserInfo{
      Result:   Result{
         Message: "success",
         Code: 200,
      },
      UserName: username,
      Passwd:   passwd,
   }
   c.JSON(http.StatusOK,result)
}

func main()  {
   r := gin.Default()
   r.POST("/user/info",handleUserInfo)
   r.Run(":9090")
}

Single file upload

func handleUpload(c *gin.Context) {
   file,err := c.FormFile("testfile")
   if err != nil {
      fmt.Printf("upload file faild,err:%v\n",err)
      return
   }

   //File upload path
   filename := fmt.Sprintf("/Users/wanghui/go/src/oldBoy/day8/tmp/%s",file.Filename)
   //file save
   err = c.SaveUploadedFile(file,filename)
   if err != nil {
      fmt.Printf("save file faild,err:%v\n",err)
      return
   }
   //State return
   c.JSON(http.StatusOK,"file upload success")
}

func main() {
   r := gin.Default()
   r.POST("/file/upload",handleUpload)
   r.Run(":9090")
}

Multi file upload

func multiHandleUpload(c *gin.Context) {
   //Multi file upload
   form,err := c.MultipartForm()
   if err != nil {
      fmt.Printf("upload file faild,err:%v\n",err)
      return
   }
   files := form.File["testfile"]

   for _,file := range files {
      filename := fmt.Sprintf("/Users/wanghui/go/src/oldBoy/day8/tmp/%s",file.Filename)
      err = c.SaveUploadedFile(file,filename)
      if err != nil {
         fmt.Printf("save file faild,err:%v\n",err)
         return
      }
   }
   //State return
   c.JSON(http.StatusOK,"file upload success")
}
func main() {
   r := gin.Default()
   r.POST("/file/upload",handleUpload)
   r.POST("/files",multiHandleUpload)
   r.Run(":9090")
}

Upload files through postman

Routing packet

func main()  {
   r := gin.Default()
   v1Group := r.Group("/v1")
   v1Group.POST("/user/info",handleUserInfo)
   v1Group.POST("/user/info2",handleUserInfo)
   r.Run(":9090")
}

Parameter binding of gin

• Why use parameter binding
  • Through the mechanism of reflection, the parameters such as querystring, form form, json and xml are automatically extracted into struct
  • Through the content type in the http protocol, identify whether it is json, xml or form

type UserInfo struct {
   UserName  string  `form:"username" json:"username" binding:"required"`
   Passwd    string  `form:"passwd" json:"passwd" binding:"required"`
   Age       int    `form:"age" json:"age" binding:"required"`
   Sex       string  `form:"sex" json:"sex" binding:"required"`
}

func PostUserInfo(c *gin.Context) {
   var UserInfo UserInfo
   //Form binding, using pointers
   err := c.ShouldBind(&UserInfo)
   if err != nil {
      return
   }
   c.JSON(http.StatusOK,UserInfo)
}

func PostUserInfoJson(c *gin.Context) {
   var UserInfo UserInfo
   //Form binding, using pointers
   err := c.ShouldBindJSON(&UserInfo)
   if err != nil {
      return
   }
   c.JSON(http.StatusOK,UserInfo)
}

func GetUserInfoJson(c *gin.Context) {
   var UserInfo UserInfo
   //Form binding, using pointers
   err := c.ShouldBindJSON(&UserInfo)
   if err != nil {
      return
   }
   c.JSON(http.StatusOK,UserInfo)
}

func main() {
   r := gin.Default()
   v1Group := r.Group("/v1")
   v1Group.POST("/user/infos",PostUserInfo)
   v1Group.POST("/user/infojson",PostUserInfoJson)
   v1Group.GET("/user/info",GetUserInfoJson)
   r.Run(":9090")
}

Rendering

• Rendering with gin.Context.JSON method

type UserInfo struct {
   UserName  string  `form:"username" json:"username" binding:"required"`
   Passwd    string  `form:"passwd" json:"passwd" binding:"required"`
}

func GetUserInfoJson(c *gin.Context) {
   var userInfo = &UserInfo{
      UserName: "zhansan",
      Passwd:   "aaaa",
   }
   c.XML(200,userInfo)
}

func main() {
   r := gin.Default()
   v1Group := r.Group("/v1")
   v1Group.GET("/user/info",GetUserInfoJson)
   r.Run(":9090")
}

HTML template rendering

• templates/post.html

{{ define "index.tmpl" }}
    <html><h1>
        {{ . }}
    </h1>
    <p>Using posts/index.tmpl</p>
    </html>
{{ end }}

• server.go

func HandleHtmml(c *gin.Context) {
   c.HTML(200,"index.tmpl","mmmmmmmm")
}

func main() {
   r := gin.Default()
   r.LoadHTMLGlob("./templates/*")
   r.GET("/user/info",HandleHtmml)
   r.Run(":9090")
}

gin Middleware

• In the request processing process, the gin framework adds the user's own hook function, which is called middleware
• Therefore, middleware can be used to process some public business logic, such as time-consuming statistics, log printing, login verification, etc

func StatCost(c *gin.Context) {
   //middleware
   start := time.Now()
   fmt.Printf("start \n")
   c.Next()
   lattacy := time.Since(start)
   fmt.Printf("cost Time is %dms\n", lattacy/1000/1000)
}

func funcHello(c *gin.Context) {
   fmt.Printf("request start\n")
   time.Sleep(time.Second * 3)
   c.JSON(http.StatusOK, "hello world")
}

func main() {
   r := gin.Default()
   r.Use(StatCost)
   r.GET("/hello", funcHello)
   r.Run(":9090")
}

Routing principle of gin framework

• The routing part uses: https://github.com/julienschmidt/httprouter
• For routing rules, httprouter will construct a prefix tree