golang之数据验证validator的实现

前言

在web应用中经常会遇到数据验证问题,普通的验证方法比较繁琐,这里介绍一个使用比较多的包validator

原理

将验证规则写在struct对字段tag里,再通过反射(reflect)获取struct的tag,实现数据验证。

安装

go get github.com/go-playground/validator/v10

示例

package main

import (
 "fmt"
 "github.com/go-playground/validator/v10"
)

type Users struct {
 Phone string `form:"phone" json:"phone" validate:"required"`
 Passwd string `form:"passwd" json:"passwd" validate:"required,max=20,min=6"`
 Code string `form:"code" json:"code" validate:"required,len=6"`
}

func main() {

 users := &Users{
 Phone:  "1326654487",
 Passwd:  "123",
 Code:   "123456",
 }
 validate := validator.New()
 err := validate.Struct(users)
 if err != nil {
 for _, err := range err.(validator.ValidationErrors) {
 fmt.Println(err)//Key: 'Users.Passwd' Error:Field validation for 'Passwd' failed on the 'min' tag
 return
 }
 }
 return
}

验证规则

  • required :必填
  • email:验证字符串是email格式;例:“email”
  • url:这将验证字符串值包含有效的网址;例:“url”
  • max:字符串最大长度;例:“max=20”
  • min:字符串最小长度;例:“min=6”
  • excludesall:不能包含特殊字符;例:“excludesall=0x2C”//注意这里用十六进制表示。
  • len:字符长度必须等于n,或者数组、切片、map的len值为n,即包含的项目数;例:“len=6”
  • eq:数字等于n,或者或者数组、切片、map的len值为n,即包含的项目数;例:“eq=6”
  • ne:数字不等于n,或者或者数组、切片、map的len值不等于为n,即包含的项目数不为n,其和eq相反;例:“ne=6”
  • gt:数字大于n,或者或者数组、切片、map的len值大于n,即包含的项目数大于n;例:“gt=6”
  • gte:数字大于或等于n,或者或者数组、切片、map的len值大于或等于n,即包含的项目数大于或等于n;例:“gte=6”
  • lt:数字小于n,或者或者数组、切片、map的len值小于n,即包含的项目数小于n;例:“lt=6”
  • lte:数字小于或等于n,或者或者数组、切片、map的len值小于或等于n,即包含的项目数小于或等于n;例:“lte=6”

跨字段验证

如想实现比较输入密码和确认密码是否一致等类似场景

  • eqfield=Field: 必须等于 Field 的值;
  • nefield=Field: 必须不等于 Field 的值;
  • gtfield=Field: 必须大于 Field 的值;
  • gtefield=Field: 必须大于等于 Field 的值;
  • ltfield=Field: 必须小于 Field 的值;
  • ltefield=Field: 必须小于等于 Field 的值;
  • eqcsfield=Other.Field: 必须等于 struct Other 中 Field 的值;
  • necsfield=Other.Field: 必须不等于 struct Other 中 Field 的值;
  • gtcsfield=Other.Field: 必须大于 struct Other 中 Field 的值;
  • gtecsfield=Other.Field: 必须大于等于 struct Other 中 Field 的值;
  • ltcsfield=Other.Field: 必须小于 struct Other 中 Field 的值;
  • ltecsfield=Other.Field: 必须小于等于 struct Other 中 Field 的值;

示例

type UserReg struct {
 Passwd string `form:"passwd" json:"passwd" validate:"required,max=20,min=6"`
 Repasswd string `form:"repasswd" json:"repasswd" validate:"required,max=20,min=6,eqfield=Passwd"`
}

示例验证了Passwd,和Repasswd值是否相等。如想了解更多类型,请参考文档 https://godoc.org/gopkg.in/go-playground/validator.v10

自定义验证类型

示例:

package main

import (
 "fmt"
 "github.com/go-playground/validator/v10"
)

type Users struct {
 Name string `form:"name" json:"name" validate:"required,CustomValidationErrors"`//包含自定义函数
 Age uint8 `form:"age" json:"age" validate:"required,gt=18"`
 Passwd string `form:"passwd" json:"passwd" validate:"required,max=20,min=6"`
 Code string `form:"code" json:"code" validate:"required,len=6"`
}

func main() {

 users := &Users{
 Name:  "admin",
 Age:  12,
 Passwd:  "123",
 Code:   "123456",
 }
 validate := validator.New()
 //注册自定义函数
 _=validate.RegisterValidation("CustomValidationErrors", CustomValidationErrors)
 err := validate.Struct(users)
 if err != nil {
 for _, err := range err.(validator.ValidationErrors) {
 fmt.Println(err)//Key: 'Users.Name' Error:Field validation for 'Name' failed on the 'CustomValidationErrors' tag
 return
 }
 }
 return
}

func CustomValidationErrors(fl validator.FieldLevel) bool {
return fl.Field().String() != "admin"
}

翻译错误信息为中文

通过以上示例我们看到,validator默认的错误提示信息类似如下

Key: 'Users.Name' Error:Field validation for 'Name' failed on the 'CustomValidationErrors' tag

显然这并不是我们想要,如想翻译成中文,或其他语言怎么办?go-playground上提供了很好的解决方法。

先自行安装需要的两个包

https://github.com/go-playground/locales
https://github.com/go-playground/universal-translator

执行:

go get github.com/go-playground/universal-translator
go get github.com/go-playground/locales

示例:

package main

import (
 "fmt"
 "github.com/go-playground/locales/zh"
 ut "github.com/go-playground/universal-translator"
 "github.com/go-playground/validator/v10"
 zh_translations "github.com/go-playground/validator/v10/translations/zh"
)

type Users struct {
 Name string `form:"name" json:"name" validate:"required"`
 Age uint8 `form:"age" json:"age" validate:"required,gt=18"`
 Passwd string `form:"passwd" json:"passwd" validate:"required,max=20,min=6"`
 Code string `form:"code" json:"code" validate:"required,len=6"`
}

func main() {
 users := &Users{
 Name:  "admin",
 Age:  12,
 Passwd:  "123",
 Code:   "123456",
 }
 uni := ut.New(zh.New())
 trans, _ := uni.GetTranslator("zh")
 validate := validator.New()
 //验证器注册翻译器
 err := zh_translations.RegisterDefaultTranslations(validate, trans)
 if err!=nil {
 fmt.Println(err)
 }
 err = validate.Struct(users)
 if err != nil {
 for _, err := range err.(validator.ValidationErrors) {
 fmt.Println(err.Translate(trans))//Age必须大于18
 return
 }
 }

 return
}

输出:

Age必须大于18

照着做没有成功(可能有遗漏吧),最后还是翻看了一下源代码,在<https://github.com/go-playground/validator/blob/master/validator_instance.go,第137行

// RegisterTagNameFunc registers a function to get alternate names for StructFields.
//
// eg. to use the names which have been specified for JSON representations of structs, rather than normal Go field names:
//
// validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
//  name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
//  if name == "-" {
//   return ""
//  }
//  return name
// })

其实原理就是注册一个函数,将struct tag里添加的中文名 作为备用名。

package main

import (
 "fmt"
 "github.com/go-playground/locales/zh"
 ut "github.com/go-playground/universal-translator"
 "github.com/go-playground/validator/v10"
 zh_translations "github.com/go-playground/validator/v10/translations/zh"
 "reflect"
)

type Users struct {
 Name string `form:"name" json:"name" validate:"required" label:"用户名"`
 Age uint8 `form:"age" json:"age" validate:"required,gt=18" label:"年龄"`
 Passwd string `form:"passwd" json:"passwd" validate:"required,max=20,min=6"`
 Code string `form:"code" json:"code" validate:"required,len=6"`
}

func main() {
 users := &Users{
 Name:  "admin",
 Age:  12,
 Passwd:  "123",
 Code:   "123456",
 }
 uni := ut.New(zh.New())
 trans, _ := uni.GetTranslator("zh")
 validate := validator.New()
 //注册一个函数,获取struct tag里自定义的label作为字段名
 validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
 name:=fld.Tag.Get("label")
 return name
 })
 //注册翻译器
 err := zh_translations.RegisterDefaultTranslations(validate, trans)
 if err!=nil {
 fmt.Println(err)
 }
 err = validate.Struct(users)
 if err != nil {
 for _, err := range err.(validator.ValidationErrors) {
 fmt.Println(err.Translate(trans))//年龄必须大于18
 return
 }
 }

 return
}

输出结果:

年龄必须大于18

gin 内置的validator

gin已经支持go-playground / validator / v10进行验证。在此处查看有关标签用法的完整文档。

以下只提供了一个绑定ShouldBindWith示例,如需了解更多方法,进入这里

示例

package main

import (
 "fmt"
 "github.com/go-playground/locales/zh"
 ut "github.com/go-playground/universal-translator"
 "github.com/go-playground/validator/v10"
 "net/http"
 "reflect"
 "strings"
 "time"

 "github.com/gin-gonic/gin"
 "github.com/gin-gonic/gin/binding"
 zh_translations "github.com/go-playground/validator/v10/translations/zh"
)
var trans ut.Translator
// Booking contains binded and validated data.
type Booking struct {
 CheckIn time.Time `form:"check_in" json:"check_in" binding:"required,bookabledate" time_format:"2006-01-02" label:"输入时间"`
 CheckOut time.Time `form:"check_out" json:"check_out" binding:"required,gtfield=CheckIn" time_format:"2006-01-02" label:"输出时间"`
}

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()
 uni := ut.New(zh.New())
 trans, _ = uni.GetTranslator("zh")

 if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
 //注册翻译器
 _= zh_translations.RegisterDefaultTranslations(v, trans)
 //注册自定义函数
 _=v.RegisterValidation("bookabledate", bookableDate)

 //注册一个函数,获取struct tag里自定义的label作为字段名
 v.RegisterTagNameFunc(func(fld reflect.StructField) string {
 name:=fld.Tag.Get("label")
 return name
 })
 //根据提供的标记注册翻译
 v.RegisterTranslation("bookabledate", trans, func(ut ut.Translator) error {
 return ut.Add("bookabledate", "{0}不能早于当前时间或{1}格式错误!", true)
 }, func(ut ut.Translator, fe validator.FieldError) string {
 t, _ := ut.T("bookabledate", fe.Field(), fe.Field())
 return t
 })

 }
 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 {
 errs := err.(validator.ValidationErrors)

 fmt.Println(errs.Translate(trans))
 //for _, e := range errs {
 // // can translate each error one at a time.
 // fmt.Println(e.Translate(trans))
 //}
 c.JSON(http.StatusBadRequest, gin.H{"error": errs.Translate(trans)})
 }
}

运行程序,执行以下命令

$ curl "localhost:8085/bookable?check_in=2018-04-16&check_out=2018-04-16"

结果:

{"error":{"Booking.输入时间":"输入时间不能早于当前时间或输入时间格式错误!","Booking.输出时间":"输出时间必须大于CheckIn"}}

查看以上结果我们发现翻译还是不太完美,如规则中有gtfield的情况,字段(CheckIn)并没有被翻译。所以通过struct添加label的方式并不能从根本上解决字段翻译问题。为了得到想要的结果,就需要将错误信息做单独处理再输出。

先定义翻译库

var BookingTrans =map[string]string{"CheckIn":"输入时间","CheckOut":"输出时间"}

再定义翻译函数

func TransTagName(libTans,err interface{}) interface{} {
 switch err.(type) {
 case validator.ValidationErrorsTranslations:
 var errs map[string]string
 errs = make(map[string]string,0)
 for k,v:=range err.(validator.ValidationErrorsTranslations){
 for key,value:=range libTans.(map[string]string) {
 v=strings.Replace(v,key,value,-1)
 }
 errs[k] = v
 }
 return errs
 case string:
 var errs string
 for key,value:=range libTans.(map[string]string) {
 errs=strings.Replace(errs,key,value,-1)
 }
 return errs
 default:
 return err
 }
}

将原来翻译错误信息的地方

errs.Translate(trans)

修改为

msg:=TransTagName(BookingTrans,errs.Translate(trans))
fmt.Println(msg)

结果

{"error":{"Booking.输入时间":"输入时间不能早于当前时间或输入时间格式错误!","Booking.输出时间":"输出时间必须大于输入时间"}}

小结:

1.gin 已经支持validator最新的v10。

2.validator数据验证顺序struct字段从上往下,单个字段规则(binding:"gt=0,lt=2`),先左后右。

参考:

https://github.com/go-playground/validator

https://github.com/gin-gonic/gin

https://gitissue.com/issues/5d06a73965d56f73569b825f

https://segmentfault.com/a/1190000022527284

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