Golang Gin(下)
Model binding and validation
To bind a request body into a type, use model binding. We currently support binding of JSON, XML, YAML and standard form values (foo=bar&boo=baz).
Gin uses go-playground/validator/v10 for validation. Check the full docs on tags usage here.
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".
Also, Gin provides two sets of methods for binding:
- Type - Must bind
- Methods -
Bind,BindJSON,BindXML,BindQuery,BindYAML,BindHeader - Behavior - These methods use
MustBindWithunder the hood. If there is a binding error, the request is aborted withc.AbortWithError(400, err).SetType(ErrorTypeBind). This sets the response status code to 400 and theContent-Typeheader is set totext/plain; charset=utf-8. Note that if you try to set the response code after this, it will result in a warning[GIN-debug] [WARNING] Headers were already written. Wanted to override status code 400 with 422. If you wish to have greater control over the behavior, consider using theShouldBindequivalent method.
- Methods -
- Type - Should bind
- Methods -
ShouldBind,ShouldBindJSON,ShouldBindXML,ShouldBindQuery,ShouldBindYAML,ShouldBindHeader - Behavior - These methods use
ShouldBindWithunder the hood. If there is a binding error, the error is returned and it is the developer's responsibility to handle the request and error appropriately.
- Methods -
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 MustBindWith or ShouldBindWith.
You can also specify that specific fields are required. If a field is decorated with binding:"required" and has a empty value when binding, an error will be returned.
// Binding from JSON type Login struct { User string `form:"user" json:"user" xml:"user" binding:"required"` Password string `form:"password" json:"password" xml:"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 err := c.ShouldBindJSON(&json); err != nil { c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()}) return } if json.User != "manu" || json.Password != "123" { c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"}) return } c.JSON(http.StatusOK, gin.H{"status": "you are logged in"}) }) // Example for binding XML ( // <?xml version="1.0" encoding="UTF-8"?> // <root> // <user>user</user> // <password>123</password> // </root>) router.POST("/loginXML", func(c *gin.Context) { var xml Login if err := c.ShouldBindXML(&xml); err != nil { c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()}) return } if xml.User != "manu" || xml.Password != "123" { c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"}) return } c.JSON(http.StatusOK, gin.H{"status": "you are logged in"}) }) // 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 err := c.ShouldBind(&form); err != nil { c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()}) return } if form.User != "manu" || form.Password != "123" { c.JSON(http.StatusUnauthorized, gin.H{"status": "unauthorized"}) return } c.JSON(http.StatusOK, gin.H{"status": "you are logged in"}) }) // Listen and serve on 0.0.0.0:8080 router.Run(":8080") }
Sample request
$ curl -v -X POST \ http://localhost:8080/loginJSON \ -H 'content-type: application/json' \ -d '{ "user": "manu" }' > POST /loginJSON HTTP/1.1 > Host: localhost:8080 > User-Agent: curl/7.51.0 > Accept: */* > content-type: application/json > Content-Length: 18 > * upload completely sent off: 18 out of 18 bytes < HTTP/1.1 400 Bad Request < Content-Type: application/json; charset=utf-8 < Date: Fri, 04 Aug 2017 03:51:31 GMT < Content-Length: 100 < {"error":"Key: 'Login.Password' Error:Field validation for 'Password' failed on the 'required' tag"}
Skip validate
When running the above example using the above the curl command, it returns error. Because the example use binding:"required" for Password. If use binding:"-" for Password, then it will not return error when running the above example again.
Custom Validators
It is also possible to register custom validators. See the example code.
package main import ( "net/http" "time" "github.com/gin-gonic/gin" "github.com/gin-gonic/gin/binding" "github.com/go-playground/validator/v10" ) // Booking contains binded and validated data. type Booking struct { CheckIn time.Time `form:"check_in" binding:"required,bookabledate" time_format:"2006-01-02"` CheckOut time.Time `form:"check_out" binding:"required,gtfield=CheckIn" time_format:"2006-01-02"` } var bookableDate validator.Func = func(fl validator.FieldLevel) bool { date, ok := fl.Field().Interface().(time.Time) if ok { today := time.Now() if today.After(date) { return false } } return true } func main() { route := gin.Default() if v, ok := binding.Validator.Engine().(*validator.Validate); ok { v.RegisterValidation("bookabledate", bookableDate) } route.GET("/bookable", getBookable) route.Run(":8085") } func getBookable(c *gin.Context) { var b Booking if err := c.ShouldBindWith(&b, binding.Query); err == nil { c.JSON(http.StatusOK, gin.H{"message": "Booking dates are valid!"}) } else { c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()}) } }
$ curl "localhost:8085/bookable?check_in=2030-04-16&check_out=2030-04-17" {"message":"Booking dates are valid!"} $ curl "localhost:8085/bookable?check_in=2030-03-10&check_out=2030-03-09" {"error":"Key: 'Booking.CheckOut' Error:Field validation for 'CheckOut' failed on the 'gtfield' tag"} $ curl "localhost:8085/bookable?check_in=2000-03-09&check_out=2000-03-10" {"error":"Key: 'Booking.CheckIn' Error:Field validation for 'CheckIn' failed on the 'bookabledate' tag"}%
Struct level validations can also be registered this way. See the struct-lvl-validation example to learn more.
Only Bind Query String
ShouldBindQuery function only binds the query params and not the post data. See the detail information.
package main import ( "log" "github.com/gin-gonic/gin" ) type Person struct { Name string `form:"name"` Address string `form:"address"` } func main() { route := gin.Default() route.Any("/testing", startPage) route.Run(":8085") } func startPage(c *gin.Context) { var person Person if c.ShouldBindQuery(&person) == nil { log.Println("====== Only Bind By Query String ======") log.Println(person.Name) log.Println(person.Address) } c.String(200, "Success") }
Bind Query String or Post Data
See the detail information.
package main import ( "log" "time" "github.com/gin-gonic/gin" ) type Person struct { Name string `form:"name"` Address string `form:"address"` Birthday time.Time `form:"birthday" time_format:"2006-01-02" time_utc:"1"` CreateTime time.Time `form:"createTime" time_format:"unixNano"` UnixTime time.Time `form:"unixTime" time_format:"unix"` } 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/master/binding/binding.go#L48 if c.ShouldBind(&person) == nil { log.Println(person.Name) log.Println(person.Address) log.Println(person.Birthday) log.Println(person.CreateTime) log.Println(person.UnixTime) } c.String(200, "Success") }
Test it with:
$ curl -X GET "localhost:8085/testing?name=appleboy&address=xyz&birthday=1992-03-15&createTime=1562400033000000123&unixTime=1562400033"
Bind Uri
See the detail information.
package main import "github.com/gin-gonic/gin" type Person struct { ID string `uri:"id" binding:"required,uuid"` Name string `uri:"name" binding:"required"` } func main() { route := gin.Default() route.GET("/:name/:id", func(c *gin.Context) { var person Person if err := c.ShouldBindUri(&person); err != nil { c.JSON(400, gin.H{"msg": err}) return } c.JSON(200, gin.H{"name": person.Name, "uuid": person.ID}) }) route.Run(":8088") }
Test it with:
$ curl -v localhost:8088/thinkerou/987fbc97-4bed-5078-9f07-9141ba07c9f3 $ curl -v localhost:8088/thinkerou/not-uuid
Bind Header
package main import ( "fmt" "github.com/gin-gonic/gin" ) type testHeader struct { Rate int `header:"Rate"` Domain string `header:"Domain"` } func main() { r := gin.Default() r.GET("/", func(c *gin.Context) { h := testHeader{} if err := c.ShouldBindHeader(&h); err != nil { c.JSON(200, err) } fmt.Printf("%#v\n", h) c.JSON(200, gin.H{"Rate": h.Rate, "Domain": h.Domain}) }) r.Run() // client // curl -H "rate:300" -H "domain:music" 127.0.0.1:8080/ // output // {"Domain":"music","Rate":300} }
Bind HTML checkboxes
See the detail information
main.go
... type myForm struct { Colors []string `form:"colors[]"` } ... func formHandler(c *gin.Context) { var fakeForm myForm c.ShouldBind(&fakeForm) c.JSON(200, gin.H{"color": fakeForm.Colors}) } ...
form.html
<form action="/" method="POST"> <p>Check some colors</p> <label for="red">Red</label> <input type="checkbox" name="colors[]" value="red" id="red"> <label for="green">Green</label> <input type="checkbox" name="colors[]" value="green" id="green"> <label for="blue">Blue</label> <input type="checkbox" name="colors[]" value="blue" id="blue"> <input type="submit"> </form>
result:
{"color":["red","green","blue"]}
Multipart/Urlencoded binding
type ProfileForm struct { Name string `form:"name" binding:"required"` Avatar *multipart.FileHeader `form:"avatar" binding:"required"` // or for multiple files // Avatars []*multipart.FileHeader `form:"avatar" binding:"required"` } func main() { router := gin.Default() router.POST("/profile", func(c *gin.Context) { // you can bind multipart form with explicit binding declaration: // c.ShouldBindWith(&form, binding.Form) // or you can simply use autobinding with ShouldBind method: var form ProfileForm // in this case proper binding will be automatically selected if err := c.ShouldBind(&form); err != nil { c.String(http.StatusBadRequest, "bad request") return } err := c.SaveUploadedFile(form.Avatar, form.Avatar.Filename) if err != nil { c.String(http.StatusInternalServerError, "unknown error") return } // db.Save(&form) c.String(http.StatusOK, "ok") }) router.Run(":8080") }
Test it with:
$ curl -X POST -v --form name=user --form "avatar=@./avatar.png" http://localhost:8080/profile
XML, JSON, YAML and ProtoBuf 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}) }) r.GET("/someProtoBuf", func(c *gin.Context) { reps := []int64{int64(1), int64(2)} label := "test" // The specific definition of protobuf is written in the testdata/protoexample file. data := &protoexample.Test{ Label: &label, Reps: reps, } // Note that data becomes binary data in the response // Will output protoexample.Test protobuf serialized data c.ProtoBuf(http.StatusOK, data) }) // Listen and serve on 0.0.0.0:8080 r.Run(":8080") }
SecureJSON
Using SecureJSON to prevent json hijacking. Default prepends "while(1)," to response body if the given struct is array values.
func main() { r := gin.Default() // You can also use your own secure json prefix // r.SecureJsonPrefix(")]}',\n") r.GET("/someJSON", func(c *gin.Context) { names := []string{"lena", "austin", "foo"} // Will output : while(1);["lena","austin","foo"] c.SecureJSON(http.StatusOK, names) }) // Listen and serve on 0.0.0.0:8080 r.Run(":8080") }
JSONP
Using JSONP to request data from a server in a different domain. Add callback to response body if the query parameter callback exists.
func main() { r := gin.Default() r.GET("/JSONP", func(c *gin.Context) { data := gin.H{ "foo": "bar", } //callback is x // Will output : x({\"foo\":\"bar\"}) c.JSONP(http.StatusOK, data) }) // Listen and serve on 0.0.0.0:8080 r.Run(":8080") // client // curl http://127.0.0.1:8080/JSONP?callback=x }
AsciiJSON
Using AsciiJSON to Generates ASCII-only JSON with escaped non-ASCII characters.
func main() { r := gin.Default() r.GET("/someJSON", func(c *gin.Context) { data := gin.H{ "lang": "GO语言", "tag": "<br>", } // will output : {"lang":"GO\u8bed\u8a00","tag":"\u003cbr\u003e"} c.AsciiJSON(http.StatusOK, data) }) // Listen and serve on 0.0.0.0:8080 r.Run(":8080") }
PureJSON
Normally, JSON replaces special HTML characters with their unicode entities, e.g. < becomes \u003c. If you want to encode such characters literally, you can use PureJSON instead. This feature is unavailable in Go 1.6 and lower.
func main() { r := gin.Default() // Serves unicode entities r.GET("/json", func(c *gin.Context) { c.JSON(200, gin.H{ "html": "<b>Hello, world!</b>", }) }) // Serves literal characters r.GET("/purejson", func(c *gin.Context) { c.PureJSON(200, gin.H{ "html": "<b>Hello, world!</b>", }) }) // 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") }
Serving data from file
func main() { router := gin.Default() router.GET("/local/file", func(c *gin.Context) { c.File("local/file.go") }) var fs http.FileSystem = // ... router.GET("/fs/file", func(c *gin.Context) { c.FileFromFS("fs/file.go", fs) }) }
Serving data from reader
func main() { router := gin.Default() router.GET("/someDataFromReader", func(c *gin.Context) { response, err := http.Get("https://raw.githubusercontent.com/gin-gonic/logo/master/color.png") if err != nil || response.StatusCode != http.StatusOK { c.Status(http.StatusServiceUnavailable) return } reader := response.Body defer reader.Close() contentLength := response.ContentLength contentType := response.Header.Get("Content-Type") extraHeaders := map[string]string{ "Content-Disposition": `attachment; filename="gopher.png"`, } c.DataFromReader(http.StatusOK, contentLength, contentType, reader, extraHeaders) }) router.Run(":8080") }
HTML rendering
Using LoadHTMLGlob() or LoadHTMLFiles()
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") }
templates/index.tmpl
<html>
<h1>
{{ .title }}
</h1>
</html>
Using templates with same name in different directories
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") }
templates/posts/index.tmpl
{{ define "posts/index.tmpl" }}
<html><h1>
{{ .title }}
</h1>
<p>Using posts/index.tmpl</p>
</html>
{{ end }}
templates/users/index.tmpl
{{ define "users/index.tmpl" }}
<html><h1>
{{ .title }}
</h1>
<p>Using users/index.tmpl</p>
</html>
{{ end }}
Custom Template renderer
You can also use your own html template render
import "html/template" func main() { router := gin.Default() html := template.Must(template.ParseFiles("file1", "file2")) router.SetHTMLTemplate(html) router.Run(":8080") }
Custom Delimiters
You may use custom delims
r := gin.Default() r.Delims("{[{", "}]}") r.LoadHTMLGlob("/path/to/templates")
Custom Template Funcs
See the detail example code.
main.go
import ( "fmt" "html/template" "net/http" "time" "github.com/gin-gonic/gin" ) func formatAsDate(t time.Time) string { year, month, day := t.Date() return fmt.Sprintf("%d%02d/%02d", year, month, day) } func main() { router := gin.Default() router.Delims("{[{", "}]}") router.SetFuncMap(template.FuncMap{ "formatAsDate": formatAsDate, }) router.LoadHTMLFiles("./testdata/template/raw.tmpl") router.GET("/raw", func(c *gin.Context) { c.HTML(http.StatusOK, "raw.tmpl", gin.H{ "now": time.Date(2017, 07, 01, 0, 0, 0, 0, time.UTC), }) }) router.Run(":8080") }
raw.tmpl
Date: {[{.now | formatAsDate}]}
Result:
Date: 2017/07/01
Multitemplate
Gin allow by default use only one html.Template. Check a multitemplate render for using features like go 1.6 block template.
Redirects
Issuing a HTTP redirect is easy. Both internal and external locations are supported.
r.GET("/test", func(c *gin.Context) { c.Redirect(http.StatusMovedPermanently, "http://www.google.com/") })
Issuing a HTTP redirect from POST. Refer to issue: #444
r.POST("/test", func(c *gin.Context) { c.Redirect(http.StatusFound, "/foo") })
Issuing a Router redirect, use HandleContext like below.
r.GET("/test", func(c *gin.Context) { c.Request.URL.Path = "/test2" r.HandleContext(c) }) r.GET("/test2", func(c *gin.Context) { c.JSON(200, gin.H{"hello": "world"}) })
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
When starting new Goroutines 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 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
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() }
Support Let's Encrypt
example for 1-line LetsEncrypt HTTPS servers.
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")) }
example for custom autocert manager.
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)) }
Run multiple service using Gin
See the question and try the following example:
package main import ( "log" "net/http" "time" "github.com/gin-gonic/gin" "golang.org/x/sync/errgroup" ) var ( g errgroup.Group ) func router01() http.Handler { e := gin.New() e.Use(gin.Recovery()) e.GET("/", func(c *gin.Context) { c.JSON( http.StatusOK, gin.H{ "code": http.StatusOK, "error": "Welcome server 01", }, ) }) return e } func router02() http.Handler { e := gin.New() e.Use(gin.Recovery()) e.GET("/", func(c *gin.Context) { c.JSON( http.StatusOK, gin.H{ "code": http.StatusOK, "error": "Welcome server 02", }, ) }) return e } func main() { server01 := &http.Server{ Addr: ":8080", Handler: router01(), ReadTimeout: 5 * time.Second, WriteTimeout: 10 * time.Second, } server02 := &http.Server{ Addr: ":8081", Handler: router02(), ReadTimeout: 5 * time.Second, WriteTimeout: 10 * time.Second, } g.Go(func() error { err := server01.ListenAndServe() if err != nil && err != http.ErrServerClosed { log.Fatal(err) } return err }) g.Go(func() error { err := server02.ListenAndServe() if err != nil && err != http.ErrServerClosed { log.Fatal(err) } return err }) if err := g.Wait(); err != nil { log.Fatal(err) } }
Graceful shutdown or restart
There are a few approaches you can use to perform a graceful shutdown or restart. You can make use of third-party packages specifically built for that, or you can manually do the same with the functions and methods from the built-in packages.
Third-party packages
We can use fvbock/endless to replace the default ListenAndServe. Refer to issue #296 for more details.
router := gin.Default() router.GET("/", handler) // [...] endless.ListenAndServe(":4242", router)
Alternatives:
- manners: A polite Go HTTP server that shuts down gracefully.
- graceful: Graceful is a Go package enabling graceful shutdown of an http.Handler server.
- grace: Graceful restart & zero downtime deploy for Go servers.
Manually
In case you are using Go 1.8 or a later version, you may not need to use those libraries. Consider using http.Server's built-in Shutdown() method for graceful shutdowns. The example below describes its usage, and we've got more examples using gin here.
// +build go1.8 package main import ( "context" "log" "net/http" "os" "os/signal" "syscall" "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, } // Initializing the server in a goroutine so that // it won't block the graceful shutdown handling below go func() { if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed { log.Fatalf("listen: %s\n", err) } }() // Wait for interrupt signal to gracefully shutdown the server with // a timeout of 5 seconds. quit := make(chan os.Signal) // kill (no param) default send syscall.SIGTERM // kill -2 is syscall.SIGINT // kill -9 is syscall.SIGKILL but can't be catch, so don't need add it signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM) <-quit log.Println("Shutting down server...") // The context is used to inform the server it has 5 seconds to finish // the request it is currently handling ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) defer cancel() if err := srv.Shutdown(ctx); err != nil { log.Fatal("Server forced to shutdown:", err) } log.Println("Server exiting") }
Build a single binary with templates
You can build a server into a single binary containing templates by using go-assets.
func main() { r := gin.New() t, err := loadTemplate() if err != nil { panic(err) } r.SetHTMLTemplate(t) r.GET("/", func(c *gin.Context) { c.HTML(http.StatusOK, "/html/index.tmpl",nil) }) r.Run(":8080") } // loadTemplate loads templates embedded by go-assets-builder func loadTemplate() (*template.Template, error) { t := template.New("") for name, file := range Assets.Files { defer file.Close() if file.IsDir() || !strings.HasSuffix(name, ".tmpl") { continue } h, err := ioutil.ReadAll(file) if err != nil { return nil, err } t, err = t.New(name).Parse(string(h)) if err != nil { return nil, err } } return t, nil }
See a complete example in the https://github.com/gin-gonic/examples/tree/master/assets-in-binary directory.
Bind form-data request with custom struct
The follow example using custom struct:
type StructA struct { FieldA string `form:"field_a"` } type StructB struct { NestedStruct StructA FieldB string `form:"field_b"` } type StructC struct { NestedStructPointer *StructA FieldC string `form:"field_c"` } type StructD struct { NestedAnonyStruct struct { FieldX string `form:"field_x"` } FieldD string `form:"field_d"` } func GetDataB(c *gin.Context) { var b StructB c.Bind(&b) c.JSON(200, gin.H{ "a": b.NestedStruct, "b": b.FieldB, }) } func GetDataC(c *gin.Context) { var b StructC c.Bind(&b) c.JSON(200, gin.H{ "a": b.NestedStructPointer, "c": b.FieldC, }) } func GetDataD(c *gin.Context) { var b StructD c.Bind(&b) c.JSON(200, gin.H{ "x": b.NestedAnonyStruct, "d": b.FieldD, }) } func main() { r := gin.Default() r.GET("/getb", GetDataB) r.GET("/getc", GetDataC) r.GET("/getd", GetDataD) r.Run() }
Using the command curl command result:
$ curl "http://localhost:8080/getb?field_a=hello&field_b=world" {"a":{"FieldA":"hello"},"b":"world"} $ curl "http://localhost:8080/getc?field_a=hello&field_c=world" {"a":{"FieldA":"hello"},"c":"world"} $ curl "http://localhost:8080/getd?field_x=hello&field_d=world" {"d":"world","x":{"FieldX":"hello"}}
Try to bind body into different structs
The normal methods for binding request body consumes c.Request.Body and they cannot be called multiple times.
type formA struct { Foo string `json:"foo" xml:"foo" binding:"required"` } type formB struct { Bar string `json:"bar" xml:"bar" binding:"required"` } func SomeHandler(c *gin.Context) { objA := formA{} objB := formB{} // This c.ShouldBind consumes c.Request.Body and it cannot be reused. if errA := c.ShouldBind(&objA); errA == nil { c.String(http.StatusOK, `the body should be formA`) // Always an error is occurred by this because c.Request.Body is EOF now. } else if errB := c.ShouldBind(&objB); errB == nil { c.String(http.StatusOK, `the body should be formB`) } else { ... } }
For this, you can use c.ShouldBindBodyWith.
func SomeHandler(c *gin.Context) { objA := formA{} objB := formB{} // This reads c.Request.Body and stores the result into the context. if errA := c.ShouldBindBodyWith(&objA, binding.JSON); errA == nil { c.String(http.StatusOK, `the body should be formA`) // At this time, it reuses body stored in the context. } else if errB := c.ShouldBindBodyWith(&objB, binding.JSON); errB == nil { c.String(http.StatusOK, `the body should be formB JSON`) // And it can accepts other formats } else if errB2 := c.ShouldBindBodyWith(&objB, binding.XML); errB2 == nil { c.String(http.StatusOK, `the body should be formB XML`) } else { ... } }
c.ShouldBindBodyWithstores body into the context before binding. This has a slight impact to performance, so you should not use this method if you are enough to call binding at once.- This feature is only needed for some formats --
JSON,XML,MsgPack,ProtoBuf. For other formats,Query,Form,FormPost,FormMultipart, can be called byc.ShouldBind()multiple times without any damage to performance (See #1341).
http2 server push
http.Pusher is supported only go1.8+. See the golang blog for detail information.
package main import ( "html/template" "log" "github.com/gin-gonic/gin" ) var html = template.Must(template.New("https").Parse(` <html> <head> <title>Https Test</title> <script src="/assets/app.js"></script> </head> <body> <h1 style="color:red;">Welcome, Ginner!</h1> </body> </html> `)) func main() { r := gin.Default() r.Static("/assets", "./assets") r.SetHTMLTemplate(html) r.GET("/", func(c *gin.Context) { if pusher := c.Writer.Pusher(); pusher != nil { // use pusher.Push() to do server push if err := pusher.Push("/assets/app.js", nil); err != nil { log.Printf("Failed to push: %v", err) } } c.HTML(200, "https", gin.H{ "status": "success", }) }) // Listen and Server in https://127.0.0.1:8080 r.RunTLS(":8080", "./testdata/server.pem", "./testdata/server.key") }
Define format for the log of routes
The default log of routes is:
[GIN-debug] POST /foo --> main.main.func1 (3 handlers) [GIN-debug] GET /bar --> main.main.func2 (3 handlers) [GIN-debug] GET /status --> main.main.func3 (3 handlers)
If you want to log this information in given format (e.g. JSON, key values or something else), then you can define this format with gin.DebugPrintRouteFunc. In the example below, we log all routes with standard log package but you can use another log tools that suits of your needs.
import ( "log" "net/http" "github.com/gin-gonic/gin" ) func main() { r := gin.Default() gin.DebugPrintRouteFunc = func(httpMethod, absolutePath, handlerName string, nuHandlers int) { log.Printf("endpoint %v %v %v %v\n", httpMethod, absolutePath, handlerName, nuHandlers) } r.POST("/foo", func(c *gin.Context) { c.JSON(http.StatusOK, "foo") }) r.GET("/bar", func(c *gin.Context) { c.JSON(http.StatusOK, "bar") }) r.GET("/status", func(c *gin.Context) { c.JSON(http.StatusOK, "ok") }) // Listen and Server in http://0.0.0.0:8080 r.Run() }
Set and get a cookie
import ( "fmt" "github.com/gin-gonic/gin" ) func main() { router := gin.Default() router.GET("/cookie", func(c *gin.Context) { cookie, err := c.Cookie("gin_cookie") if err != nil { cookie = "NotSet" c.SetCookie("gin_cookie", "test", 3600, "/", "localhost", false, true) } fmt.Printf("Cookie value: %s \n", cookie) }) router.Run() }
Testing
The net/http/httptest package is preferable way for HTTP testing.
package main func setupRouter() *gin.Engine { r := gin.Default() r.GET("/ping", func(c *gin.Context) { c.String(200, "pong") }) return r } func main() { r := setupRouter() r.Run(":8080") }
Test for code example above:
package main import ( "net/http" "net/http/httptest" "testing" "github.com/stretchr/testify/assert" ) func TestPingRoute(t *testing.T) { router := setupRouter() w := httptest.NewRecorder() req, _ := http.NewRequest("GET", "/ping", nil) router.ServeHTTP(w, req) assert.Equal(t, 200, w.Code) assert.Equal(t, "pong", w.Body.String()) }
