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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
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
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
至此我们发现大部分错误信息已经翻译成中文，但字段名（Age）还是没有翻译，为了将字段名翻译成中文，查了一些资料，http://blog.iis7.com/article/197866.htm>，
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
