翻译 | Gin Web Framework

傷城~ 2022-12-16 13:10 158阅读 0赞

> 文章开始时间 2020年10月20日，预期 2020年10月27日 完成

# Gin Web Framework #

![color.png][]

Gin 是用 Go（Golang）编写的 Web 框架。 它具有类似于 martini 的API，其性能比 [httprouter][] 快40倍。 如果您需要性能和良好的生产力，您会喜欢Gin的。

--------------------

### Gin Web Framework ###

*  Gin Web Framework
 *   *  安装
     *  快速开始
     *  基准测试
     *  Gin v1. stable
     *  Build with \[jsoniter\](https://github.com/json-iterator/go)
     *  API 示例
     *   *  Using GET, POST, PUT, PATCH, DELETE and OPTIONS
         *  路径参数
         *  查询字符串参数
         *  Multipart/Urlencoded 表单参数
         *  其他例子: 查询字符串参数 + post 表单
         *  Map as querystring or postform parameters
         *  上传文件
         *   *  单个文件
             *  多个文件
         *  分组路由
         *  默认情况下没有中间的 Gin
         *  使用中间件 Using middleware
         *  Custom Recovery behavior
         *  How to write log file
         *  Custom Log Format
         *  Controlling Log output coloring
         *  Model binding and validation
         *  Custom Validators
         *  Only Bind Query String
         *  Bind Query String or Post Data
         *  Bind Uri
         *  Bind Header
         *  Bind HTML checkboxes
         *  Multipart/Urlencoded binding
         *  XML, JSON, YAML and ProtoBuf rendering
         *   *  SecureJSON
             *  JSONP
             *  AsciiJSON
             *  PureJSON
         *  Serving static files
         *  Serving data from file
         *  Serving data from reader
         *  HTML rendering
         *   *  Custom Template renderer
             *  Custom Delimiters
             *  Custom Template Funcs
         *  Multitemplate
         *  Redirects
         *  Custom Middleware
         *  Using BasicAuth() middleware
         *  Goroutines inside a middleware
         *  Custom HTTP configuration
         *  Support Let's Encrypt
         *  Run multiple service using Gin
         *  Graceful shutdown or restart
         *   *  Third-party packages
             *  Manually
         *  Build a single binary with templates
         *  Bind form-data request with custom struct
         *  Try to bind body into different structs
         *  http2 server push
         *  Define format for the log of routes
         *  设置和获取 cookie
     *  测试

--------------------

## 安装 ##

要安装Gin软件包，您需要安装Go并首先设置 Go workspace。

1.  首先你需要
2.  首先需要安装 [Go][]（**需要1.11+版本**），然后可以使用下面的Go命令安装Gin。

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

1.  在你的代码中 import 进来:

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

1.  （可选）import `net / http`。 如需使用诸如 `http.StatusOK` 之类的常量时，这是必需的。

import "net/http"

## 快速开始 ##

# assume the following codes in example.go file
    $ cat example.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

## 基准测试 ##

> 对原始数据根据 (1) 进行了重排

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

*  (1): 在固定时间内完成总重复次数，越高越好
 *  (2): 单次重复持续时间 (ns/op), 越低越好
 *  (3): 堆内存 (B/op), 越低越好
 *  (4): 每次重复的平均分配数 (allocs/op), 越低越好

## Gin v1. stable ##

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

## Build with [jsoniter][] ##

Gin uses `encoding/json` as default json package but you can change to [jsoniter][] by build from other tags.

$ go build -tags=jsoniter .

## API 示例 ##

这里有一些现成的示例 [Gin examples repository][].

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

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
    }

### 路径参数 ###

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")
    }

### 查询字符串参数 ###

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 表单参数 ###

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")
    }

### 其他例子: 查询字符串参数 + post 表单 ###

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

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

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

### 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

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]

### 上传文件 ###

#### 单个文件 ####

References issue [\#774][774] and detail [example code][].

`file.Filename` **SHOULD NOT** be trusted. See [`Content-Disposition` on MDN][Content-Disposition_ on MDN] and [\#1693][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.

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`:

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

#### 多个文件 ####

See the detail [example code][example code 1].

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`:

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"

### 分组路由 ###

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")
    }

### 默认情况下没有中间的 Gin ###

Use

r := gin.New()

instead of

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

### 使用中间件 Using middleware ###

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 ###

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 ###

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 ###

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:

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:

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**][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 `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.

// 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][example code 2].

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][detail information 1].

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][detail information 2].

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][detail information 3]

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][example code 3].

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][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)
    }

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][fvbock_endless] to replace the default `ListenAndServe`. Refer to issue [\#296][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()][Shutdown] method for graceful shutdowns. The example below describes its usage, and we’ve got more examples using gin [here][here 1].

// +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.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][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()
    }

### 设置和获取 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()
    }

## 测试 ##

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())
    }

[color.png]: https://raw.githubusercontent.com/gin-gonic/logo/master/color.png
[httprouter]: https://github.com/julienschmidt/httprouter
[Go]: https://golang.org/
[jsoniter]: https://github.com/json-iterator/go
[Gin examples repository]: https://github.com/gin-gonic/examples
[774]: https://github.com/gin-gonic/gin/issues/774
[example code]: https://github.com/gin-gonic/examples/tree/master/upload-file/single
[Content-Disposition_ on MDN]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition#Directives
[1693]: https://github.com/gin-gonic/gin/issues/1693
[example code 1]: https://github.com/gin-gonic/examples/tree/master/upload-file/multiple
[go-playground_validator_v10]: https://github.com/go-playground/validator
[here]: https://godoc.org/github.com/go-playground/validator#hdr-Baked_In_Validators_and_Tags
[example code 2]: https://github.com/gin-gonic/examples/tree/master/custom-validation/server.go
[Struct level validations]: https://github.com/go-playground/validator/releases/tag/v8.7
[struct-lvl-validation example]: https://github.com/gin-gonic/examples/tree/master/struct-lvl-validations
[detail information]: https://github.com/gin-gonic/gin/issues/742#issuecomment-315953017
[detail information 1]: https://github.com/gin-gonic/gin/issues/742#issuecomment-264681292
[detail information 2]: https://github.com/gin-gonic/gin/issues/846
[detail information 3]: https://github.com/gin-gonic/gin/issues/129#issuecomment-124260092
[example code 3]: https://github.com/gin-gonic/examples/tree/master/template
[a multitemplate render]: https://github.com/gin-contrib/multitemplate
[444]: https://github.com/gin-gonic/gin/issues/444
[question]: https://github.com/gin-gonic/gin/issues/346
[fvbock_endless]: https://github.com/fvbock/endless
[296]: https://github.com/gin-gonic/gin/issues/296
[manners]: https://github.com/braintree/manners
[graceful]: https://github.com/tylerb/graceful
[grace]: https://github.com/facebookgo/grace
[Shutdown]: https://golang.org/pkg/net/http/#Server.Shutdown
[here 1]: https://github.com/gin-gonic/examples/tree/master/graceful-shutdown
[go-assets]: https://github.com/jessevdk/go-assets
[1341]: https://github.com/gin-gonic/gin/pull/1341
[golang blog]: https://blog.golang.org/h2push