#Gin Web Framework

Gin is a web framework written in Golang. It features a martini-like API with much better performance, up to 40 times faster. If you need performance and good productivity, you will love Gin.
Check out the official web site

##Gin is new, will it be supported?

Yes, Gin is an internal project of my upcoming startup. We developed it and we are going to continue using and improve it.

##Roadmap

• Performance improments, reduce allocation and garbage collection overhead
• Fix bugs
• Ask our designer for a cool logo
• Add tons of unit tests and benchmarks
• Improve logging system
• Improve JSON/XML validation using bindings
• Improve XML support
• Improve documentation
• Add more cool middlewares, for example redis catching (this also helps developers to understand the framework)
• Continuous integration

Start using it

Run:

go get github.com/gin-gonic/gin

Then import it in your Golang code:

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

##API Examples

Create most basic PING/PONG HTTP endpoint

package main

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

func main() {
	r := gin.Default()
	r.GET("/ping", func(c *gin.Context) {
		c.String(200, "pong")
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Using GET, POST, PUT, PATCH and DELETE

func main() {
	// Creates a gin router + logger and recovery (crash-free) middlewares
	r := gin.Default()

	r.GET("/someGet", getting)
	r.POST("/somePost", posting)
	r.PUT("/somePut", putting)
	r.DELETE("/someDelete", deleting)
	r.PATCH("/somePatch", patching)

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Parameters in path

func main() {
	r := gin.Default()

	r.GET("/user/:name", func(c *gin.Context) {
		name := c.Params.ByName("name")
		message := "Hello " + name
		c.String(200, message)
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Grouping routes

func main() {
	r := gin.Default()

	// Simple group: v1
	v1 := r.Group("/v1")
	{
		v1.POST("/login", loginEndpoint)
		v1.POST("/submit", submitEndpoint)
		v1.POST("/read", readEndpoint)
	}

	// Simple group: v2
	v2 := r.Group("/v2")
	{
		v2.POST("/login", loginEndpoint)
		v2.POST("/submit", submitEndpoint)
		v2.POST("/read", readEndpoint)
	}

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Blank Gin without middlewares by default

Use

r := gin.New()

instead of

r := gin.Default()

Using middlewares

func main() {
	// Creates a router without any middleware by default
	r := gin.New()

	// Global middlewares
	r.Use(gin.Logger())
	r.Use(gin.Recovery())

	// Per route middlewares, you can add as many as you desire.
	r.GET("/benchmark", MyBenchLogger(), benchEndpoint)

	// Authorization group
	// authorized := r.Group("/", AuthRequired())
	// exactly the same than:
	authorized := r.Group("/")
	// per group middlewares! 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 server on 0.0.0.0:8080
	r.Run(":8080")
}

JSON parsing and validation

type LoginJSON struct {
	User     string `json:"user" binding:"required"`
	Password string `json:"password" binding:"required"`
}

func main() {
	r := gin.Default()

	r.POST("/login", func(c *gin.Context) {
		var json LoginJSON

		// If EnsureBody returns false, it will write automatically the error
		// in the HTTP stream and return a 400 error. If you want custom error
		// handling you should use: c.ParseBody(interface{}) error
		if c.EnsureBody(&json) {
			if json.User == "manu" && json.Password == "123" {
				c.JSON(200, gin.H{"status": "you are logged in"})
			} else {
				c.JSON(401, gin.H{"status": "unauthorized"})
			}
		}
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

XML, and JSON rendering

func main() {
	r := gin.Default()

	// gin.H is a shortcup for map[string]interface{}
	r.GET("/someJSON", func(c *gin.Context) {
		c.JSON(200, gin.H{"message": "hey", "status": 200})
	})

	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(200, msg)
	})

	r.GET("/someXML", func(c *gin.Context) {
		c.XML(200, gin.H{"message": "hey", "status": 200})
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

####HTML rendering

Using LoadHTMLTemplates()

func main() {
	r := gin.Default()
	r.LoadHTMLTemplates("templates/*")
	r.GET("/index", func(c *gin.Context) {
		obj := gin.H{"title": "Main website"}
		c.HTML(200, "index.tmpl", obj)
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

You can also use your own html template render

import "html/template"

func main() {
	r := gin.Default()
	html := template.Must(template.ParseFiles("file1", "file2"))
	r.HTMLTemplates = html

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Custom Middlewares

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)
	}
}

func main() {
	r := gin.New()
	r.Use(Logger())

	r.GET("/test", func(c *gin.Context) {
		example := r.Get("example").(string)

		// it would print: "12345"
		log.Println(example)
	})

	// Listen and server on 0.0.0.0:8080
	r.Run(":8080")
}

Custom HTTP configuration

Use http.ListenAndServe() directly, like this:

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

or

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()
}