Gin Web Framework

$ cat test.go

package main
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() // listen and serve on 0.0.0.0:8080
}

Benchmarks

Gin v1. stable

Start using it

$ go get github.com/gin-gonic/gin

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

import "net/http"

Use a vendor tool like Govendor

$ go get github.com/kardianos/govendor

$ mkdir -p ~/go/src/github.com/myusername/project && cd "$_"

$ govendor init
$ govendor fetch github.com/gin-gonic/gin@v1.2

$ curl https://raw.githubusercontent.com/gin-gonic/gin/master/examples/basic/main.go > main.go

$ go run main.go

API Examples

Using GET, POST, PUT, PATCH, DELETE and OPTIONS

func main() {
	// Disable Console Color
	// gin.DisableConsoleColor()
	// Creates a gin router with default middleware:
	// logger and recovery (crash-free) middleware
	router := gin.Default()
	router.GET("/someGet", getting)
	router.POST("/somePost", posting)
	router.PUT("/somePut", putting)
	router.DELETE("/someDelete", deleting)
	router.PATCH("/somePatch", patching)
	router.HEAD("/someHead", head)
	router.OPTIONS("/someOptions", options)
	// By default it serves on :8080 unless a
	// PORT environment variable was defined.
	router.Run()
	// router.Run(":3000") for a hard coded port
}

Parameters in path

func main() {
	router := gin.Default()
	// This handler will match /user/john but will not match neither /user/ or /user
	router.GET("/user/:name", func(c *gin.Context) {
		name := c.Param("name")
		c.String(http.StatusOK, "Hello %s", name)
	})
	// However, this one will match /user/john/ and also /user/john/send
	// If no other routers match /user/john, it will redirect to /user/john/
	router.GET("/user/:name/*action", func(c *gin.Context) {
		name := c.Param("name")
		action := c.Param("action")
		message := name + " is " + action
		c.String(http.StatusOK, message)
	})
	router.Run(":8080")
}

Querystring parameters

func main() {
	router := gin.Default()
	// Query string parameters are parsed using the existing underlying request object.
	// The request responds to a url matching: /welcome?firstname=Jane&lastname=Doe
	router.GET("/welcome", func(c *gin.Context) {
		firstname := c.DefaultQuery("firstname", "Guest")
		lastname := c.Query("lastname") // shortcut for c.Request.URL.Query().Get("lastname")
		c.String(http.StatusOK, "Hello %s %s", firstname, lastname)
	})
	router.Run(":8080")
}

Multipart/Urlencoded Form

func main() {
	router := gin.Default()
	router.POST("/form_post", func(c *gin.Context) {
		message := c.PostForm("message")
		nick := c.DefaultPostForm("nick", "anonymous")
		c.JSON(200, gin.H{
			"status": "posted",
			"message": message,
			"nick": nick,
		})
	})
	router.Run(":8080")
}

Another example: query + post form

POST /post?id=1234&page=1 HTTP/1.1
Content-Type: application/x-www-form-urlencoded
name=manu&message=this_is_great

func main() {
	router := gin.Default()
	router.POST("/post", func(c *gin.Context) {
		id := c.Query("id")
		page := c.DefaultQuery("page", "0")
		name := c.PostForm("name")
		message := c.PostForm("message")
		fmt.Printf("id: %s; page: %s; name: %s; message: %s", id, page, name, message)
	})
	router.Run(":8080")
}

id: 1234; page: 1; name: manu; message: this_is_great

Upload files

Single file

func main() {
	router := gin.Default()
	router.POST("/upload", func(c *gin.Context) {
		// single file
		file, _ := c.FormFile("file")
		log.Println(file.Filename)
		c.String(http.StatusOK, fmt.Printf("'%s' uploaded!", file.Filename))
	})
	router.Run(":8080")
}

curl -X POST http://localhost:8080/upload \
 -F "file=@/Users/appleboy/test.zip" \
 -H "Content-Type: multipart/form-data"

Multiple files

func main() {
	router := gin.Default()
	router.POST("/upload", func(c *gin.Context) {
		// Multipart form
		form, _ := c.MultipartForm()
		files := form.File["upload[]"]
		for _, file := range files {
			log.Println(file.Filename)
		}
		c.String(http.StatusOK, fmt.Printf("%d files uploaded!", len(files)))
	})
	router.Run(":8080")
}

curl -X POST http://localhost:8080/upload \
 -F "upload[]=@/Users/appleboy/test1.zip" \
 -F "upload[]=@/Users/appleboy/test2.zip" \
 -H "Content-Type: multipart/form-data"

Grouping routes

func main() {
	router := gin.Default()
	// Simple group: v1
	v1 := router.Group("/v1")
	{
		v1.POST("/login", loginEndpoint)
		v1.POST("/submit", submitEndpoint)
		v1.POST("/read", readEndpoint)
	}
	// Simple group: v2
	v2 := router.Group("/v2")
	{
		v2.POST("/login", loginEndpoint)
		v2.POST("/submit", submitEndpoint)
		v2.POST("/read", readEndpoint)
	}
	router.Run(":8080")
}

Blank Gin without middleware by default

r := gin.New()

r := gin.Default()

Using middleware

func main() {
	// Creates a router without any middleware by default
	r := gin.New()
	// Global middleware
	r.Use(gin.Logger())
	r.Use(gin.Recovery())
	// Per route middleware, you can add as many as you desire.
	r.GET("/benchmark", MyBenchLogger(), benchEndpoint)
	// Authorization group
	// authorized := r.Group("/", AuthRequired())
	// exactly the same as:
	authorized := r.Group("/")
	// per group middleware! in this case we use the custom created
	// AuthRequired() middleware just in the "authorized" group.
	authorized.Use(AuthRequired())
	{
		authorized.POST("/login", loginEndpoint)
		authorized.POST("/submit", submitEndpoint)
		authorized.POST("/read", readEndpoint)
		// nested group
		testing := authorized.Group("testing")
		testing.GET("/analytics", analyticsEndpoint)
	}
	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

Model binding and validation

// Binding from JSON
type Login struct {
	User string `form:"user" json:"user" binding:"required"`
	Password string `form:"password" json:"password" binding:"required"`
}
func main() {
	router := gin.Default()
	// Example for binding JSON ({"user": "manu", "password": "123"})
	router.POST("/loginJSON", func(c *gin.Context) {
		var json Login
		if c.BindJSON(&json) == nil {
			if json.User == "manu" && json.Password == "123" {
				c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
			} else {
				c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
			}
		}
	})
	// Example for binding a HTML form (user=manu&password=123)
	router.POST("/loginForm", func(c *gin.Context) {
		var form Login
		// This will infer what binder to use depending on the content-type header.
		if c.Bind(&form) == nil {
			if form.User == "manu" && form.Password == "123" {
				c.JSON(http.StatusOK, gin.H{"status": "you are logged in"})
			} else {
				c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"})
			}
		}
	})
	// Listen and serve on 0.0.0.0:8080
	router.Run(":8080")
}

Bind Query String

package main
import "log"
import "github.com/gin-gonic/gin"
type Person struct {
	Name string `form:"name"`
	Address string `form:"address"`
}
func main() {
	route := gin.Default()
	route.GET("/testing", startPage)
	route.Run(":8085")
}
func startPage(c *gin.Context) {
	var person Person
	// If `GET`, only `Form` binding engine (`query`) used.
	// If `POST`, first checks the `content-type` for `JSON` or `XML`, then uses `Form` (`form-data`).
	// See more at https://github.com/gin-gonic/gin/blob/develop/binding/binding.go#L45
	if c.Bind(&person) == nil {
		log.Println(person.Name)
		log.Println(person.Address)
	}
	c.String(200, "Success")
}

Multipart/Urlencoded binding

package main
import (
	"github.com/gin-gonic/gin"
)
type LoginForm struct {
	User string `form:"user" binding:"required"`
	Password string `form:"password" binding:"required"`
}
func main() {
	router := gin.Default()
	router.POST("/login", func(c *gin.Context) {
		// you can bind multipart form with explicit binding declaration:
		// c.MustBindWith(&form, binding.Form)
		// or you can simply use autobinding with Bind method:
		var form LoginForm
		// in this case proper binding will be automatically selected
		if c.Bind(&form) == nil {
			if form.User == "user" && form.Password == "password" {
				c.JSON(200, gin.H{"status": "you are logged in"})
			} else {
				c.JSON(401, gin.H{"status": "unauthorized"})
			}
		}
	})
	router.Run(":8080")
}

$ curl -v --form user=user --form password=password http://localhost:8080/login

XML, JSON and YAML rendering

func main() {
	r := gin.Default()
	// gin.H is a shortcut for map[string]interface{}
	r.GET("/someJSON", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
	})
	r.GET("/moreJSON", func(c *gin.Context) {
		// You also can use a struct
		var msg struct {
			Name string `json:"user"`
			Message string
			Number int
		}
		msg.Name = "Lena"
		msg.Message = "hey"
		msg.Number = 123
		// Note that msg.Name becomes "user" in the JSON
		// Will output : {"user": "Lena", "Message": "hey", "Number": 123}
		c.JSON(http.StatusOK, msg)
	})
	r.GET("/someXML", func(c *gin.Context) {
		c.XML(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
	})
	r.GET("/someYAML", func(c *gin.Context) {
		c.YAML(http.StatusOK, gin.H{"message": "hey", "status": http.StatusOK})
	})
	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

Serving static files

func main() {
	router := gin.Default()
	router.Static("/assets", "./assets")
	router.StaticFS("/more_static", http.Dir("my_file_system"))
	router.StaticFile("/favicon.ico", "./resources/favicon.ico")
	// Listen and serve on 0.0.0.0:8080
	router.Run(":8080")
}

HTML rendering

func main() {
	router := gin.Default()
	router.LoadHTMLGlob("templates/*")
	//router.LoadHTMLFiles("templates/template1.html", "templates/template2.html")
	router.GET("/index", func(c *gin.Context) {
		c.HTML(http.StatusOK, "index.tmpl", gin.H{
			"title": "Main website",
		})
	})
	router.Run(":8080")
}

<html>
	<h1>
		{{ .title }}
	</h1>
</html>

func main() {
	router := gin.Default()
	router.LoadHTMLGlob("templates/**/*")
	router.GET("/posts/index", func(c *gin.Context) {
		c.HTML(http.StatusOK, "posts/index.tmpl", gin.H{
			"title": "Posts",
		})
	})
	router.GET("/users/index", func(c *gin.Context) {
		c.HTML(http.StatusOK, "users/index.tmpl", gin.H{
			"title": "Users",
		})
	})
	router.Run(":8080")
}

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

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

import "html/template"
func main() {
	router := gin.Default()
	html := template.Must(template.ParseFiles("file1", "file2"))
	router.SetHTMLTemplate(html)
	router.Run(":8080")
}

	r := gin.Default()
	r.Delims("{[{", "}]}")
	r.LoadHTMLGlob("/path/to/templates"))

Add custom template funcs

	...
	
	func formatAsDate(t time.Time) string {
		year, month, day := t.Date()
		return fmt.Sprintf("%d/%02d/%02d", year, month, day)
	}
	
	...
	
	router.SetFuncMap(template.FuncMap{
		"formatAsDate": formatAsDate,
	})
	
	...
	
	router.GET("/raw", func(c *Context) {
		c.HTML(http.StatusOK, "raw.tmpl", map[string]interface{}{
			"now": time.Date(2017, 07, 01, 0, 0, 0, 0, time.UTC),
		})
	})
	
	...

Date: {[{.now | formatAsDate}]}

Date: 2017年07月01日

Multitemplate

Redirects

r.GET("/test", func(c *gin.Context) {
	c.Redirect(http.StatusMovedPermanently, "http://www.google.com/")
})

Custom Middleware

func Logger() gin.HandlerFunc {
	return func(c *gin.Context) {
		t := time.Now()
		// Set example variable
		c.Set("example", "12345")
		// before request
		c.Next()
		// after request
		latency := time.Since(t)
		log.Print(latency)
		// access the status we are sending
		status := c.Writer.Status()
		log.Println(status)
	}
}
func main() {
	r := gin.New()
	r.Use(Logger())
	r.GET("/test", func(c *gin.Context) {
		example := c.MustGet("example").(string)
		// it would print: "12345"
		log.Println(example)
	})
	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

Using BasicAuth() middleware

// simulate some private data
var secrets = gin.H{
	"foo": gin.H{"email": "foo@bar.com", "phone": "123433"},
	"austin": gin.H{"email": "austin@example.com", "phone": "666"},
	"lena": gin.H{"email": "lena@guapa.com", "phone": "523443"},
}
func main() {
	r := gin.Default()
	// Group using gin.BasicAuth() middleware
	// gin.Accounts is a shortcut for map[string]string
	authorized := r.Group("/admin", gin.BasicAuth(gin.Accounts{
		"foo": "bar",
		"austin": "1234",
		"lena": "hello2",
		"manu": "4321",
	}))
	// /admin/secrets endpoint
	// hit "localhost:8080/admin/secrets
	authorized.GET("/secrets", func(c *gin.Context) {
		// get user, it was set by the BasicAuth middleware
		user := c.MustGet(gin.AuthUserKey).(string)
		if secret, ok := secrets[user]; ok {
			c.JSON(http.StatusOK, gin.H{"user": user, "secret": secret})
		} else {
			c.JSON(http.StatusOK, gin.H{"user": user, "secret": "NO SECRET :("})
		}
	})
	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

Goroutines inside a middleware

func main() {
	r := gin.Default()
	r.GET("/long_async", func(c *gin.Context) {
		// create copy to be used inside the goroutine
		cCp := c.Copy()
		go func() {
			// simulate a long task with time.Sleep(). 5 seconds
			time.Sleep(5 * time.Second)
			// note that you are using the copied context "cCp", IMPORTANT
			log.Println("Done! in path " + cCp.Request.URL.Path)
		}()
	})
	r.GET("/long_sync", func(c *gin.Context) {
		// simulate a long task with time.Sleep(). 5 seconds
		time.Sleep(5 * time.Second)
		// since we are NOT using a goroutine, we do not have to copy the context
		log.Println("Done! in path " + c.Request.URL.Path)
	})
	// Listen and serve on 0.0.0.0:8080
	r.Run(":8080")
}

Custom HTTP configuration

func main() {
	router := gin.Default()
	http.ListenAndServe(":8080", router)
}

func main() {
	router := gin.Default()
	s := &http.Server{
		Addr: ":8080",
		Handler: router,
		ReadTimeout: 10 * time.Second,
		WriteTimeout: 10 * time.Second,
		MaxHeaderBytes: 1 << 20,
	}
	s.ListenAndServe()
}

Support Let's Encrypt

package main
import (
	"log"
	"github.com/gin-gonic/autotls"
	"github.com/gin-gonic/gin"
)
func main() {
	r := gin.Default()
	// Ping handler
	r.GET("/ping", func(c *gin.Context) {
		c.String(200, "pong")
	})
	log.Fatal(autotls.Run(r, "example1.com", "example2.com"))
}

package main
import (
	"log"
	"github.com/gin-gonic/autotls"
	"github.com/gin-gonic/gin"
	"golang.org/x/crypto/acme/autocert"
)
func main() {
	r := gin.Default()
	// Ping handler
	r.GET("/ping", func(c *gin.Context) {
		c.String(200, "pong")
	})
	m := autocert.Manager{
		Prompt: autocert.AcceptTOS,
		HostPolicy: autocert.HostWhitelist("example1.com", "example2.com"),
		Cache: autocert.DirCache("/var/www/.cache"),
	}
	log.Fatal(autotls.RunWithManager(r, &m))
}

Graceful restart or stop

router := gin.Default()
router.GET("/", handler)
// [...]
endless.ListenAndServe(":4242", router)

// +build go1.8
package main
import (
	"context"
	"log"
	"net/http"
	"os"
	"os/signal"
	"time"
	"github.com/gin-gonic/gin"
)
func main() {
	router := gin.Default()
	router.GET("/", func(c *gin.Context) {
		time.Sleep(5 * time.Second)
		c.String(http.StatusOK, "Welcome Gin Server")
	})
	srv := &http.Server{
		Addr: ":8080",
		Handler: router,
	}
	go func() {
		// service connections
		if err := srv.ListenAndServe(); err != nil {
			log.Printf("listen: %s\n", err)
		}
	}()
	// Wait for interrupt signal to gracefully shutdown the server with
	// a timeout of 5 seconds.
	quit := make(chan os.Signal)
	signal.Notify(quit, os.Interrupt)
	<-quit
	log.Println("Shutdown Server ...")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := srv.Shutdown(ctx); err != nil {
		log.Fatal("Server Shutdown:", err)
	}
	log.Println("Server exist")
}

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