简介

本文接着上文(Golang GinWeb框架3-自定义日志格式和输出方式/启禁日志颜色)继续探索GinWeb框架

模型绑定和验证

使用模型绑定来绑定请求体到一个Go类型上. 目前支持JSON,XML,YAML以及标准表单(如foo=bar&boo=baz)的绑定.

Gin使用go-playground/validator/v10包来验证请求, 关于tags在验证中使用详见(#hdr-Baked_In_Validators_and_Tags)

注意:绑定前请确认结构体中需要绑定的字段标签与绑定类型一致,比如绑定JSON,设置标签: json:”fieldname”

Gin提供两种方式(类型)来完成绑定:

• Must bind

1. 方法: Bind, BindJSON, BindXML, BindQuery, BindYAML, BindHeader

2. 特点: 这些方法底层使用MustBindWith方法. 如果出现绑定错误, 请求将以状态码400返回失败信息:c.AbortWithError(400, err).SetType(ErrorTypeBind), 响应中设置Content-Type头为text/plain; charset=utf-8.如果手动设置响应码,会警告响应头已经设置,比如提示: [GIN-debug] [WARNING] Headers were already written. Wanted to override status code 400 with 422, 如果想要更好的控制这些行为,建议使用下面对应的ShoudBind方法.

• Should bind

1. 方法: ShouldBind, ShouldBindJSON, ShouldBindXML, ShouldBindQuery, ShouldBindYAML, ShouldBindHeader

2. 特点: 这些方法底层使用ShouldBindWith. 如果出现绑定错误, 会返回错误, 开发者可以控制和恰当的处理这些错误.

当使用绑定方法时, Gin尝试根据类型头Content-Type header自动推断要使用的绑定器. 如果你已经确认需要绑定的类型,可以直接使用底层的MustBindWith或ShouldBindWith方法.

你也可以针对特殊的字段指定required标签值, 如果某个字段指定了:binding:”required”标签, 但是在绑定时该字段为空会返回错误.

如以下代码绑定JSON:

 package main
​
import (
  "github.com/gin-gonic/gin"
  "net/http"
)
​
// Binding from JSON
type Login struct {
  User string `form:"user" json:"user" xml:"user"  binding:"required"` //分别定义form,json,xml,binding等标签
  //Password string `form:"password" json:"password" xml:"password" binding:"required"`
  Password string `form:"password" json:"password" xml:"password" binding:"-"`
}
​
​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")
}
​
//模拟请求: curl -v -X POST  -H 'content-type: application/json' -d '{ "user": "manu", "password": "123" }'  

跳过验证: 与binding:”required”标签对应的是binding:”-“, 表示该字段不做绑定, 所以绑定时该字段为空不会报错.

自定义验证器

你也可以自己注册一个自定义验证器, 示例代码请参考(

 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.
// Booking结构中定义了包含绑定器和日期验证器标签
type Booking struct {
  CheckIn  time.Time `form:"check_in" binding:"required,bookabledate" time_format:"2006-01-02"`  //登记时间
  CheckOut time.Time `form:"check_out" binding:"required,gtfield=CheckIn" time_format:"2006-01-02"`  //gtfield=CheckIn表示结账时间必须大于登记时间
}
​
// 定义日期验证器
var bookableDate validator.Func = func(fl validator.FieldLevel) bool {
  date, ok := fl.Field().Interface().(time.Time)  //利用反射获取到字段值 -> 转为接口 -> 类型断言(时间类型)
  if ok {
    today := time.Now()
    if today.After(date) {  //如果当前时间在checkIn字段时间之后,返回false,即登记时间不能早于当前的时间
      return false
    }
  }
  return true
}
​
func main() {
  route := gin.Default()
  //对binding.Validator.Engine()接口进行类型断言,断言类型为Validate结构,如果断言成功,就将自定义的验证器注册到Gin内部
  if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
    // - if the key already exists, the previous validation function will be replaced. 该注册方法会将已经存在的验证器替换
    // - this method is not thread-safe it is intended that these all be registered prior to any validation
    // 注册方法不是线程安全的, 在验证开始前,需要保证所有的验证器都注册成功
    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()})
  }
}
​
//模拟请求:
// 登记时间和结账时间符合条件
//$ curl "localhost:8085/bookable?check_in=2030-04-16✓_out=2030-04-17"
//{"message":"Booking dates are valid!"}
//
// 登记时间在结账时间之后, 不满足gtfield校验规则
//$ curl "localhost:8085/bookable?check_in=2030-03-10✓_out=2030-03-09"
//{"error":"Key: 'Booking.CheckOut' Error:Field validation for 'CheckOut' failed on the 'gtfield' tag"}
//
// 登记时间在当前时间之前,不满足自定义的验证器
//$ curl "localhost:8085/bookable?check_in=2000-03-09✓_out=2000-03-10"
//{"error":"Key: 'Booking.CheckIn' Error:Field validation for 'CheckIn' failed on the 'bookabledate' tag"}%  

另外结构体级别的验证采用如下的方式注册, v.RegisterStructValidation(UserStructLevelValidation, User{}), 请参考struct-lvl-validation example(

参考文档

Gin官方仓库:

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