#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 thanks to httprouter. If you need performance and good productivity, you will love Gin.
$ cat test.go
package main
import (
"net/http"
"github.com/gin-gonic/gin"
)
func main() {
router := gin.Default()
router.GET("/", func(c *gin.Context) {
c.String(http.StatusOK, "hello world")
})
router.GET("/ping", func(c *gin.Context) {
c.String(http.StatusOK, "pong")
})
router.POST("/submit", func(c *gin.Context) {
c.String(http.StatusUnauthorized, "not authorized")
})
router.PUT("/error", func(c *gin.Context) {
c.String(http.StatusInternalServerError, "an error happened :(")
})
router.Run(":8080")
}##Gin is new, will it be supported?
Yes, Gin is an internal tool of Manu and Javi for many of our projects/start-ups. We developed it and we are going to continue using and improve it.
##Roadmap for v1.0
- Ask our designer for a cool logo
- Add tons of unit tests
- Add internal benchmarks suite
- More powerful validation API
- Improve documentation
- Add Swagger support
- Stable API
- Improve logging system
- Improve JSON/XML validation using bindings
- Improve XML support
- Flexible rendering system
- Add more cool middlewares, for example redis caching (this also helps developers to understand the framework).
- Continuous integration
- Performance improments, reduce allocation and garbage collection overhead
- Fix bugs
Obviously, you need to have Git and Go already installed to run Gin.
Run this in your terminal
go get github.com/gin-gonic/gin
Then import it in your Go code:
import "github.com/gin-gonic/gin"
##API Examples
package main
import (
"net/http"
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
r.GET("/ping", func(c *gin.Context) {
c.String(http.StatusOK, "pong")
})
// Listen and serve on 0.0.0.0:8080
r.Run(":8080")
}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)
r.HEAD("/someHead", head)
r.OPTIONS("/someOptions", options)
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}func main() {
r := gin.Default()
// This handler will match /user/john but will not match neither /user/ or /user
r.GET("/user/:name", func(c *gin.Context) {
name := c.Params.ByName("name")
message := "Hello "+name
c.String(http.StatusOK, message)
})
// However, this one will match /user/john/ and also /user/john/send
// If no other routers match /user/john, it will redirect to /user/join/
r.GET("/user/:name/*action", func(c *gin.Context) {
name := c.Params.ByName("name")
action := c.Params.ByName("action")
message := name + " is " + action
c.String(http.StatusOK, message)
})
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}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")
}###Form parameters
func main() {
r := gin.Default()
// This will respond to urls like search?firstname=Jane&lastname=Doe
r.GET("/search", func(c *gin.Context) {
// You need to call ParseForm() on the request to receive url and form params first
c.Request.ParseForm()
firstname := c.Request.Form.Get("firstname")
lastname := c.Request.Form.Get("lastname")
message := "Hello "+ firstname + lastname
c.String(http.StatusOK, message)
})
r.Run(":8080")
}###Multipart Form
package main
import (
"github.com/gin-gonic/gin"
"github.com/gin-gonic/gin/binding"
)
type LoginForm struct {
User string `form:"user" binding:"required"`
Password string `form:"password" binding:"required"`
}
func main() {
r := gin.Default()
r.POST("/login", func(c *gin.Context) {
var form LoginForm
// you can bind multipart form with explicit binding declaration:
// c.BindWith(&form, binding.Form)
// or you can simply use autobinding with Bind method:
c.Bind(&form) // in this case proper binding will be automatically selected
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"})
}
})
r.Run(":8080")
}Test it with:
$ curl -v --form user=user --form password=password https://localhost:8080/loginfunc 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")
}Use
r := gin.New()instead of
r := gin.Default()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")
}To bind a request body into a type, use model binding. We currently support binding of JSON, XML and standard form values (foo=bar&boo=baz).
Note that you need to set the corresponding binding tag on all fields you want to bind. For example, when binding from JSON, set json:"fieldname".
When using the Bind-method, Gin tries to infer the binder depending on the Content-Type header. If you are sure what you are binding, you can use BindWith.
You can also specify that specific fields are required. If a field is decorated with binding:"required" and has a empty value when binding, the current request will fail with an error.
// Binding from JSON
type LoginJSON struct {
User string `json:"user" binding:"required"`
Password string `json:"password" binding:"required"`
}
// Binding from form values
type LoginForm struct {
User string `form:"user" binding:"required"`
Password string `form:"password" binding:"required"`
}
func main() {
r := gin.Default()
// Example for binding JSON ({"user": "manu", "password": "123"})
r.POST("/loginJSON", func(c *gin.Context) {
var json LoginJSON
c.Bind(&json) // This will infer what binder to use depending on the content-type header.
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)
r.POST("/loginHTML", func(c *gin.Context) {
var form LoginForm
c.BindWith(&form, binding.Form) // You can also specify which binder to use. We support binding.Form, binding.JSON and binding.XML.
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 server on 0.0.0.0:8080
r.Run(":8080")
}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})
})
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}####Serving static files Use Engine.ServeFiles(path string, root http.FileSystem):
func main() {
r := gin.Default()
r.Static("/assets", "./assets")
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}Use the following example to serve static files at top level route of your domain. Files are being served from directory ./html.
r := gin.Default()
r.Use(static.Serve("/", static.LocalFile("html", false)))
Note: this will use httpNotFound instead of the Router's NotFound handler.
####HTML rendering
Using LoadHTMLTemplates()
func main() {
r := gin.Default()
r.LoadHTMLGlob("templates/*")
r.GET("/index", func(c *gin.Context) {
obj := gin.H{"title": "Main website"}
c.HTML(http.StatusOK, "index.tmpl", obj)
})
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}<h1>
{{ .title }}
</h1>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.SetHTMLTemplate(html)
// Listen and server on 0.0.0.0:8080
r.Run(":8080")
}#####Using layout files with templates
var baseTemplate = "main.tmpl"
r.GET("/", func(c *gin.Context) {
r.SetHTMLTemplate(template.Must(template.ParseFiles(baseTemplate, "whatever.tmpl")))
c.HTML(200, "base", data)
})main.tmpl
{{define "base"}}
<html>
<head></head>
<body>
{{template "content" .}}
</body>
</html>
{{end}}whatever.tmpl
{{define "content"}}
<h1>Hello World!</h1>
{{end}}Issuing a HTTP redirect is easy:
r.GET("/test", func(c *gin.Context) {
c.Redirect(http.StatusMovedPermanently, "https://www.google.com/")
})Both internal and external locations are supported.
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 server on 0.0.0.0:8080
r.Run(":8080")
}// simulate some private data
var secrets = gin.H{
"foo": gin.H{"email": "[email protected]", "phone": "123433"},
"austin": gin.H{"email": "[email protected]", "phone": "666"},
"lena": gin.H{"email": "[email protected]", "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 setted 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 server on 0.0.0.0:8080
r.Run(":8080")
}When starting inside a middleware or handler, you SHOULD NOT use the original context inside it, you have to use a read-only copy.
func main() {
r := gin.Default()
r.GET("/long_async", func(c *gin.Context) {
// create copy to be used inside the goroutine
c_cp := c.Copy()
go func() {
// simulate a long task with time.Sleep(). 5 seconds
time.Sleep(5 * time.Second)
// note than you are using the copied context "c_cp", IMPORTANT
log.Println("Done! in path " + c_cp.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 server on 0.0.0.0:8080
r.Run(":8080")
}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()
}