gin/README.md

# Gin Web Framework

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Gin is a web framework written in Go (Golang). It features a martini-like API with performance that is up to 40 times faster thanks to [httprouter](https://github.com/julienschmidt/httprouter). If you need performance and good productivity, you will love Gin.


## Contents

- [Gin Web Framework](#gin-web-framework)
  - [Contents](#contents)
  - [Installation](#installation)
  - [Quick start](#quick-start)
  - [Benchmarks](#benchmarks)
  - [Gin v1. stable](#gin-v1-stable)
  - [Build with jsoniter](#build-with-jsoniter)
  - [API Examples](#api-examples)
    - [Using GET, POST, PUT, PATCH, DELETE and OPTIONS](#using-get-post-put-patch-delete-and-options)
    - [Parameters in path](#parameters-in-path)
    - [Querystring parameters](#querystring-parameters)
    - [Multipart/Urlencoded Form](#multiparturlencoded-form)
    - [Another example: query + post form](#another-example-query--post-form)
    - [Map as querystring or postform parameters](#map-as-querystring-or-postform-parameters)
    - [Upload files](#upload-files)
      - [Single file](#single-file)
      - [Multiple files](#multiple-files)
    - [Grouping routes](#grouping-routes)
    - [Blank Gin without middleware by default](#blank-gin-without-middleware-by-default)
    - [Using middleware](#using-middleware)
    - [How to write log file](#how-to-write-log-file)
    - [Custom Log Format](#custom-log-format)
    - [Controlling Log output coloring](#controlling-log-output-coloring)
    - [Model binding and validation](#model-binding-and-validation)
    - [Custom Validators](#custom-validators)
    - [Only Bind Query String](#only-bind-query-string)
    - [Bind Query String or Post Data](#bind-query-string-or-post-data)
    - [Bind Uri](#bind-uri)
    - [Bind Header](#bind-header)
    - [Bind HTML checkboxes](#bind-html-checkboxes)
    - [Multipart/Urlencoded binding](#multiparturlencoded-binding)
    - [XML, JSON, YAML and ProtoBuf rendering](#xml-json-yaml-and-protobuf-rendering)
      - [SecureJSON](#securejson)
      - [JSONP](#jsonp)
      - [AsciiJSON](#asciijson)
      - [PureJSON](#purejson)
    - [Serving static files](#serving-static-files)
    - [Serving data from file](#serving-data-from-file)
    - [Serving data from reader](#serving-data-from-reader)
    - [HTML rendering](#html-rendering)
      - [Custom Template renderer](#custom-template-renderer)
      - [Custom Delimiters](#custom-delimiters)
      - [Custom Template Funcs](#custom-template-funcs)
    - [Multitemplate](#multitemplate)
    - [Redirects](#redirects)
    - [Custom Middleware](#custom-middleware)
    - [Using BasicAuth() middleware](#using-basicauth-middleware)
    - [Goroutines inside a middleware](#goroutines-inside-a-middleware)
    - [Custom HTTP configuration](#custom-http-configuration)
    - [Support Let's Encrypt](#support-lets-encrypt)
    - [Run multiple service using Gin](#run-multiple-service-using-gin)
    - [Graceful shutdown or restart](#graceful-shutdown-or-restart)
      - [Third-party packages](#third-party-packages)
      - [Manually](#manually)
    - [Build a single binary with templates](#build-a-single-binary-with-templates)
    - [Bind form-data request with custom struct](#bind-form-data-request-with-custom-struct)
    - [Try to bind body into different structs](#try-to-bind-body-into-different-structs)
    - [http2 server push](#http2-server-push)
    - [Define format for the log of routes](#define-format-for-the-log-of-routes)
    - [Set and get a cookie](#set-and-get-a-cookie)
  - [Testing](#testing)
  - [Users](#users)

## Installation

To install Gin package, you need to install Go and set your Go workspace first.

1. The first need [Go](https://golang.org/) installed (**version 1.11+ is required**), then you can use the below Go command to install Gin.

```sh
$ go get -u github.com/gin-gonic/gin
```

2. Import it in your code:

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

3. (Optional) Import `net/http`. This is required for example if using constants such as `http.StatusOK`.

```go
import "net/http"
```

## Quick start
 
```sh
# assume the following codes in example.go file
$ cat example.go
```

```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 (for windows "localhost:8080")
}
```

```
# run example.go and visit 0.0.0.0:8080/ping (for windows "localhost:8080/ping") on browser
$ go run example.go
```

## Benchmarks

Gin uses a custom version of [HttpRouter](https://github.com/julienschmidt/httprouter)

[See all benchmarks](/BENCHMARKS.md)

| Benchmark name                 |       (1) |             (2) |          (3) |             (4) |
| ------------------------------ | ---------:| ---------------:| ------------:| ---------------:|
| BenchmarkGin_GithubAll         | **43550** | **27364 ns/op** |   **0 B/op** | **0 allocs/op** |
| BenchmarkAce_GithubAll         |     40543 |     29670 ns/op |       0 B/op |     0 allocs/op |
| BenchmarkAero_GithubAll        |     57632 |     20648 ns/op |       0 B/op |     0 allocs/op |
| BenchmarkBear_GithubAll        |      9234 |    216179 ns/op |   86448 B/op |   943 allocs/op |
| BenchmarkBeego_GithubAll       |      7407 |    243496 ns/op |   71456 B/op |   609 allocs/op |
| BenchmarkBone_GithubAll        |       420 |   2922835 ns/op |  720160 B/op |  8620 allocs/op |
| BenchmarkChi_GithubAll         |      7620 |    238331 ns/op |   87696 B/op |   609 allocs/op |
| BenchmarkDenco_GithubAll       |     18355 |     64494 ns/op |   20224 B/op |   167 allocs/op |
| BenchmarkEcho_GithubAll        |     31251 |     38479 ns/op |       0 B/op |     0 allocs/op |
| BenchmarkGocraftWeb_GithubAll  |      4117 |    300062 ns/op |  131656 B/op |  1686 allocs/op |
| BenchmarkGoji_GithubAll        |      3274 |    416158 ns/op |   56112 B/op |   334 allocs/op |
| BenchmarkGojiv2_GithubAll      |      1402 |    870518 ns/op |  352720 B/op |  4321 allocs/op |
| BenchmarkGoJsonRest_GithubAll  |      2976 |    401507 ns/op |  134371 B/op |  2737 allocs/op |
| BenchmarkGoRestful_GithubAll   |       410 |   2913158 ns/op |  910144 B/op |  2938 allocs/op |
| BenchmarkGorillaMux_GithubAll  |       346 |   3384987 ns/op |  251650 B/op |  1994 allocs/op |
| BenchmarkGowwwRouter_GithubAll |     10000 |    143025 ns/op |   72144 B/op |   501 allocs/op |
| BenchmarkHttpRouter_GithubAll  |     55938 |     21360 ns/op |       0 B/op |     0 allocs/op |
| BenchmarkHttpTreeMux_GithubAll |     10000 |    153944 ns/op |   65856 B/op |   671 allocs/op |
| BenchmarkKocha_GithubAll       |     10000 |    106315 ns/op |   23304 B/op |   843 allocs/op |
| BenchmarkLARS_GithubAll        |     47779 |     25084 ns/op |       0 B/op |     0 allocs/op |
| BenchmarkMacaron_GithubAll     |      3266 |    371907 ns/op |  149409 B/op |  1624 allocs/op |
| BenchmarkMartini_GithubAll     |       331 |   3444706 ns/op |  226551 B/op |  2325 allocs/op |
| BenchmarkPat_GithubAll         |       273 |   4381818 ns/op | 1483152 B/op | 26963 allocs/op |
| BenchmarkPossum_GithubAll      |     10000 |    164367 ns/op |   84448 B/op |   609 allocs/op |
| BenchmarkR2router_GithubAll    |     10000 |    160220 ns/op |   77328 B/op |   979 allocs/op |
| BenchmarkRivet_GithubAll       |     14625 |     82453 ns/op |   16272 B/op |   167 allocs/op |
| BenchmarkTango_GithubAll       |      6255 |    279611 ns/op |   63826 B/op |  1618 allocs/op |
| BenchmarkTigerTonic_GithubAll  |      2008 |    687874 ns/op |  193856 B/op |  4474 allocs/op |
| BenchmarkTraffic_GithubAll     |       355 |   3478508 ns/op |  820744 B/op | 14114 allocs/op |
| BenchmarkVulcan_GithubAll      |      6885 |    193333 ns/op |   19894 B/op |   609 allocs/op |

- (1): Total Repetitions achieved in constant time, higher means more confident result
- (2): Single Repetition Duration (ns/op), lower is better
- (3): Heap Memory (B/op), lower is better
- (4): Average Allocations per Repetition (allocs/op), lower is better

## Gin v1. stable

- [x] Zero allocation router.
- [x] Still the fastest http router and framework. From routing to writing.
- [x] Complete suite of unit tests.
- [x] Battle tested.
- [x] API frozen, new releases will not break your code.

## Build with [jsoniter](https://github.com/json-iterator/go)

Gin uses `encoding/json` as default json package but you can change to [jsoniter](https://github.com/json-iterator/go) by build from other tags.

```sh
$ go build -tags=jsoniter .
```

## API Examples

You can find a number of ready-to-run examples at [Gin examples repository](https://github.com/gin-gonic/examples).

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

```go
func main() {
	// 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

```go
func main() {
	router := gin.Default()

	// This handler will match /user/john but will not match /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)
	})

	// For each matched request Context will hold the route definition
	router.POST("/user/:name/*action", func(c *gin.Context) {
		c.FullPath() == "/user/:name/*action" // true
	})

	router.Run(":8080")
}
```

### Querystring parameters

```go
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

```go
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
```

```go
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
```

### Map as querystring or postform parameters

```
POST /post?ids[a]=1234&ids[b]=hello HTTP/1.1
Content-Type: application/x-www-form-urlencoded

names[first]=thinkerou&names[second]=tianou
```

```go
func main() {
	router := gin.Default()

	router.POST("/post", func(c *gin.Context) {

		ids := c.QueryMap("ids")
		names := c.PostFormMap("names")

		fmt.Printf("ids: %v; names: %v", ids, names)
	})
	router.Run(":8080")
}
```

```
ids: map[b:hello a:1234]; names: map[second:tianou first:thinkerou]
```

### Upload files

#### Single file

References issue [#774](https://github.com/gin-gonic/gin/issues/774) and detail [example code](https://github.com/gin-gonic/examples/tree/master/upload-file/single).

`file.Filename` **SHOULD NOT** be trusted. See [`Content-Disposition` on MDN](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition#Directives) and [#1693](https://github.com/gin-gonic/gin/issues/1693)

> The filename is always optional and must not be used blindly by the application: path information should be stripped, and conversion to the server file system rules should be done.

```go
func main() {
	router := gin.Default()
	// Set a lower memory limit for multipart forms (default is 32 MiB)
	router.MaxMultipartMemory = 8 << 20  // 8 MiB
	router.POST("/upload", func(c *gin.Context) {
		// single file
		file, _ := c.FormFile("file")
		log.Println(file.Filename)

		// Upload the file to specific dst.
		c.SaveUploadedFile(file, dst)

		c.String(http.StatusOK, fmt.Sprintf("'%s' uploaded!", file.Filename))
	})
	router.Run(":8080")
}
```

How to `curl`:

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

#### Multiple files

See the detail [example code](https://github.com/gin-gonic/examples/tree/master/upload-file/multiple).

```go
func main() {
	router := gin.Default()
	// Set a lower memory limit for multipart forms (default is 32 MiB)
	router.MaxMultipartMemory = 8 << 20  // 8 MiB
	router.POST("/upload", func(c *gin.Context) {
		// Multipart form
		form, _ := c.MultipartForm()
		files := form.File["upload[]"]

		for _, file := range files {
			log.Println(file.Filename)

			// Upload the file to specific dst.
			c.SaveUploadedFile(file, dst)
		}
		c.String(http.StatusOK, fmt.Sprintf("%d files uploaded!", len(files)))
	})
	router.Run(":8080")
}
```

How to `curl`:

```bash
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

```go
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

Use

```go
r := gin.New()
```

instead of

```go
// Default With the Logger and Recovery middleware already attached
r := gin.Default()
```


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

	// Global middleware
	// Logger middleware will write the logs to gin.DefaultWriter even if you set with GIN_MODE=release.
	// By default gin.DefaultWriter = os.Stdout
	r.Use(gin.Logger())

	// Recovery middleware recovers from any panics and writes a 500 if there was one.
	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")
}
```

### Custom Recovery behavior
```go
func main() {
	// Creates a router without any middleware by default
	r := gin.New()

	// Global middleware
	// Logger middleware will write the logs to gin.DefaultWriter even if you set with GIN_MODE=release.
	// By default gin.DefaultWriter = os.Stdout
	r.Use(gin.Logger())

	// Recovery middleware recovers from any panics and writes a 500 if there was one.
	r.Use(gin.CustomRecovery(func(c *gin.Context, recovered interface{}) {
		if err, ok := recovered.(string); ok {
			c.String(http.StatusInternalServerError, fmt.Sprintf("error: %s", err))
		}
		c.AbortWithStatus(http.StatusInternalServerError)
	}))

	r.GET("/panic", func(c *gin.Context) {
		// panic with a string -- the custom middleware could save this to a database or report it to the user
		panic("foo")
	})

	r.GET("/", func(c *gin.Context) {
		c.String(http.StatusOK, "ohai")
	})

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

### How to write log file
```go
func main() {
    // Disable Console Color, you don't need console color when writing the logs to file.
    gin.DisableConsoleColor()

    // Logging to a file.
    f, _ := os.Create("gin.log")
    gin.DefaultWriter = io.MultiWriter(f)

    // Use the following code if you need to write the logs to file and console at the same time.
    // gin.DefaultWriter = io.MultiWriter(f, os.Stdout)

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

    router.Run(":8080")
}
```

### Custom Log Format
```go
func main() {
	router := gin.New()

	// LoggerWithFormatter middleware will write the logs to gin.DefaultWriter
	// By default gin.DefaultWriter = os.Stdout
	router.Use(gin.LoggerWithFormatter(func(param gin.LogFormatterParams) string {

		// your custom format
		return fmt.Sprintf("%s - [%s] \"%s %s %s %d %s \"%s\" %s\"\n",
				param.ClientIP,
				param.TimeStamp.Format(time.RFC1123),
				param.Method,
				param.Path,
				param.Request.Proto,
				param.StatusCode,
				param.Latency,
				param.Request.UserAgent(),
				param.ErrorMessage,
		)
	}))
	router.Use(gin.Recovery())

	router.GET("/ping", func(c *gin.Context) {
		c.String(200, "pong")
	})

	router.Run(":8080")
}
```

**Sample Output**
```
::1 - [Fri, 07 Dec 2018 17:04:38 JST] "GET /ping HTTP/1.1 200 122.767µs "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36" "
```

### Controlling Log output coloring 

By default, logs output on console should be colorized depending on the detected TTY.

Never colorize logs: 

```go
func main() {
    // Disable log's color
    gin.DisableConsoleColor()
    
    // Creates a gin router with default middleware:
    // logger and recovery (crash-free) middleware
    router := gin.Default()
    
    router.GET("/ping", func(c *gin.Context) {
        c.String(200, "pong")
    })
    
    router.Run(":8080")
}
```

Always colorize logs: 

```go
func main() {
    // Force log's color
    gin.ForceConsoleColor()
    
    // Creates a gin router with default middleware:
    // logger and recovery (crash-free) middleware
    router := gin.Default()
    
    router.GET("/ping", func(c *gin.Context) {
        c.String(200, "pong")
    })
    
    router.Run(":8080")
}
```

### 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**](https://github.com/go-playground/validator) for validation. Check the full docs on tags usage [here](https://godoc.org/github.com/go-playground/validator#hdr-Baked_In_Validators_and_Tags).

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 `MustBindWith` under the hood. If there is a binding error, the request is aborted with `c.AbortWithError(400, err).SetType(ErrorTypeBind)`. This sets the response status code to 400 and the `Content-Type` header is set to `text/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 the `ShouldBind` equivalent method.
- **Type** - Should bind
  - **Methods** - `ShouldBind`, `ShouldBindJSON`, `ShouldBindXML`, `ShouldBindQuery`, `ShouldBindYAML`, `ShouldBindHeader`
  - **Behavior** - These methods use `ShouldBindWith` under 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.

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.

```go
// 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**
```shell
$ 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](https://github.com/gin-gonic/examples/tree/master/custom-validation/server.go).

```go
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()})
	}
}
```

```console
$ 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](https://github.com/go-playground/validator/releases/tag/v8.7) can also be registered this way.
See the [struct-lvl-validation example](https://github.com/gin-gonic/examples/tree/master/struct-lvl-validations) to learn more.

### Only Bind Query String

`ShouldBindQuery` function only binds the query params and not the post data. See the [detail information](https://github.com/gin-gonic/gin/issues/742#issuecomment-315953017).

```go
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](https://github.com/gin-gonic/gin/issues/742#issuecomment-264681292).

```go
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:
```sh
$ curl -X GET "localhost:8085/testing?name=appleboy&address=xyz&birthday=1992-03-15&createTime=1562400033000000123&unixTime=1562400033"
```

### Bind Uri

See the [detail information](https://github.com/gin-gonic/gin/issues/846).

```go
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:
```sh
$ curl -v localhost:8088/thinkerou/987fbc97-4bed-5078-9f07-9141ba07c9f3
$ curl -v localhost:8088/thinkerou/not-uuid
```

### Bind Header

```go
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](https://github.com/gin-gonic/gin/issues/129#issuecomment-124260092)

main.go

```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

```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

```go
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:
```sh
$ curl -X POST -v --form name=user --form "avatar=@./avatar.png" http://localhost:8080/profile
```

### XML, JSON, YAML and ProtoBuf rendering

```go
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.

```go
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.

```go
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.

```go
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.

```go
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

```go
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

```go
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

```go
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(), LoadHTMLFiles() or LoadHTMLFilesRecursively

```go
func main() {
	router := gin.Default()
	router.LoadHTMLGlob("templates/*")
	//router.LoadHTMLFiles("templates/template1.html", "templates/template2.html")

	// load recursively all .html files in "public" folder
	//router.LoadHTMLFilesRecursively("public", []string{".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
<html>
	<h1>
		{{ .title }}
	</h1>
</html>
```

Using templates with same name in different directories

```go
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

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

templates/users/index.tmpl

```html
{{ 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

```go
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

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

#### Custom Template Funcs

See the detail [example code](https://github.com/gin-gonic/examples/tree/master/template).

main.go

```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

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

Result:
```
Date: 2017/07/01
```

### Multitemplate

Gin allow by default use only one html.Template. Check [a multitemplate render](https://github.com/gin-contrib/multitemplate) for using features like go 1.6 `block template`.

### Redirects

Issuing a HTTP redirect is easy. Both internal and external locations are supported.

```go
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](https://github.com/gin-gonic/gin/issues/444)
```go
r.POST("/test", func(c *gin.Context) {
	c.Redirect(http.StatusFound, "/foo")
})
```

Issuing a Router redirect, use `HandleContext` like below.

``` go
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

```go
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

```go
// 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.

```go
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:

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

```go
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.

```go
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.

```go
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](https://github.com/gin-gonic/gin/issues/346) and try the following example:

```go
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](https://github.com/fvbock/endless) to replace the default `ListenAndServe`. Refer to issue [#296](https://github.com/gin-gonic/gin/issues/296) for more details.

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

Alternatives:

* [manners](https://github.com/braintree/manners): A polite Go HTTP server that shuts down gracefully.
* [graceful](https://github.com/tylerb/graceful): Graceful is a Go package enabling graceful shutdown of an http.Handler server.
* [grace](https://github.com/facebookgo/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()](https://golang.org/pkg/net/http/#Server.Shutdown) method for graceful shutdowns. The example below describes its usage, and we've got more examples using gin [here](https://github.com/gin-gonic/examples/tree/master/graceful-shutdown).

```go
// +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][].

[go-assets]: https://github.com/jessevdk/go-assets

```go
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:

```go
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.

```go
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`.

```go
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.ShouldBindBodyWith` stores 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 by `c.ShouldBind()` multiple times without any damage to
performance (See [#1341](https://github.com/gin-gonic/gin/pull/1341)).

### http2 server push

http.Pusher is supported only **go1.8+**. See the [golang blog](https://blog.golang.org/h2push) for detail information.

```go
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.
```go
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

```go
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.

```go
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:

```go
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())
}
```

## Users

Awesome project lists using [Gin](https://github.com/gin-gonic/gin) web framework.

* [gorush](https://github.com/appleboy/gorush): A push notification server written in Go.
* [fnproject](https://github.com/fnproject/fn): The container native, cloud agnostic serverless platform.
* [photoprism](https://github.com/photoprism/photoprism): Personal photo management powered by Go and Google TensorFlow.
* [krakend](https://github.com/devopsfaith/krakend): Ultra performant API Gateway with middlewares.
* [picfit](https://github.com/thoas/picfit): An image resizing server written in Go.
* [brigade](https://github.com/brigadecore/brigade): Event-based Scripting for Kubernetes.
* [dkron](https://github.com/distribworks/dkron): Distributed, fault tolerant job scheduling system.