golang常用库：gorilla/mux-http路由库使用
golang常用库：配置文件解析库-viper使用
golang常用库：操作数据库的orm框架-gorm基本使用
golang常用库：字段参数验证库-validator使用

一、背景

在平常开发中，特别是在web应用开发中，为了验证输入字段的合法性，都会做一些验证操作。比如对用户提交的表单字段进行验证，或者对请求的API接口字段进行验证，验证字段的合法性，保证输入字段值的安全，防止用户的恶意请求。

一般的做法是用正则表达式，一个字段一个字段的进行验证。一个一个字段验证的话，写起来比较繁琐。那有没更好的方法，进行字段的合法性验证？有， 这就是下面要介绍的 validator 这个验证组件。

代码地址：
https://github.com/go-playground/validator

文档地址：
https://github.com/go-playground/validator/blob/master/README.md

二、功能介绍

这个验证包 github.com/go-playground/validator 验证功能非常多。

标记之间特殊符号说明

• 逗号( , )：把多个验证标记隔开。注意：隔开逗号之间不能有空格, validate:"lt=0,gt=100"，逗号那里不能有空格，否则panic
• 横线( - )：跳过该字段不验证
• 竖线( | )：使用多个验证标记，但是只需满足其中一个即可
• required：表示该字段值必输设置，且不能为默认值
• omitempty：如果字段未设置，则忽略它

范围比较验证

doc: https://github.com/go-playground/validator/blob/master/README.md#comparisons

范围验证: 切片、数组和map、字符串，验证其长度；数值，验证大小范围

• lte：小于等于参数值，validate:"lte=3" (小于等于3)
• gte：大于等于参数值，validate:"lte=0,gte=120" (大于等于0小于等于120)
• lt：小于参数值，validate:"lt=3" (小于3)
• gt：大于参数值，validate:"lt=0,gt=120" (大于0小于120)
• len：等于参数值，validate:"len=2"
• max：大于等于参数值，validate:"max=2" (大于等于2)
• min：小于等于参数值，validate:"min=2,max=10" (大于等于2小于等于10)
• ne：不等于，validate:"ne=2" (不等于2)
• oneof：只能是列举出的值其中一个，这些值必须是数值或字符串，以空格分隔，如果字符串中有空格，将字符串用单引号包围，validate:"oneof=red green"

例子：

type User struct { Name string `json:"name" validate:"min=0,max=35"` Age unit8 `json:"age" validate:"lte=0,gte=90"`}

更多功能请参看文档 validator comparisons doc

字符串验证

doc: https://github.com/go-playground/validator/blob/master/README.md#strings

• contains：包含参数子串，validate:"contains=tom" (字段的字符串值包含tom)
• excludes：包含参数子串，validate:"excludes=tom" (字段的字符串值不包含tom)
• startswith：以参数子串为前缀，validate:"startswith=golang"
• endswith：以参数子串为后缀，validate:"startswith=world"

例子：

type User struct { Name string `validate:"contains=tom"` Age int `validate:"min=1"`}

更多功能请参看文档 validator strings doc

字段验证

doc: https://github.com/go-playground/validator/blob/master/README.md#fields

eqcsfield：跨不同结构体字段验证，比如说 Struct1 Filed1，与结构体Struct2 Field2相等，

type Struct1 struct { Field1 string `validate:eqcsfield=Struct2.Field2` Struct2 struct { Field2 string }}

• necsfield：跨不同结构体字段不相等
• eqfield：同一结构体字段验证相等，最常见的就是输入2次密码验证

type User struct { Name string `validate:"lte=4"` Age int `validate:"min=20"` Password string `validate:"min=10"` Password2 string `validate:"eqfield=Password"`}

nefield：同一结构体字段验证不相等

type User struct { Name string `validate:"lte=4"` Age int `validate:"min=20"` Password string `validate:"min=10,nefield=Name"`}

• gtefield：大于等于同一结构体字段，validate:"gtefiled=Field2"
• ltefield：小于等于同一结构体字段

更多功能请参看文档：validator Fields DOC

网络验证

doc: https://github.com/go-playground/validator/blob/master/README.md#network

• ip：字段值是否包含有效的IP地址，validate:"ip"
• ipv4：字段值是否包含有效的ipv4地址，validate:"ipv4"
• ipv6：字段值是否包含有效的ipv6地址，validate:"ipv6"
• uri：字段值是否包含有效的uri，validate:"uri"
• url：字段值是否包含有效的uri，validate:"url"

更多功能请参看文档：validator network DOC

Format

doc: https://github.com/go-playground/validator/blob/master/README.md#format

base64：字段值是否包含有效的base64值

更多功能请参看文档 validator strings doc

其他

请参看文档: https://github.com/go-playground/validator/blob/master/README.md#other

三、安装

go get:

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

在文件中引用validator包：

import "github.com/go-playground/validator/v10"

四、validator使用

文档：https://github.com/go-playground/validator/blob/master/README.md#examples

例子1：验证单个字段变量值

validation1.go

package mainimport ( "fmt" "github.com/go-playground/validator/v10")func main() { validate := validator.New() var boolTest bool err := validate.Var(boolTest, "required") if err != nil { fmt.Println(err) } var stringTest string = "" err = validate.Var(stringTest, "required") if err != nil { fmt.Println(err) } var emailTest string = "test@126.com" err = validate.Var(emailTest, "email") if err != nil { fmt.Println(err) } else { fmt.Println("success") // 输出： success。 说明验证成功 } emailTest2 := "test.126.com" errs := validate.Var(emailTest2, "required,email") if errs != nil { fmt.Println(errs) // 输出: Key: "" Error:Field validation for "" failed on the "email" tag。验证失败 } fmt.Println("\r\nEnd!!") }

运行输出：

go run simple1.go
Key: '' Error:Field validation for '' failed on the 'required' tag
Key: '' Error:Field validation for '' failed on the 'required' tag
success
Key: '' Error:Field validation for '' failed on the 'email' tag

End!!

例子2：验证结构体struct

from：struct validate

validation_struct.go，这个程序还列出了效验出错字段的一些信息，

package mainimport ( "fmt" "github.com/go-playground/validator/v10")type User struct { FirstName string `validate:"required"` LastName string `validate:"required"` Age uint8 `validate:"gte=0,lte=130"` Email string `validate:"required,email"` Addresses []*Address `validate:"required,dive,required"`}type Address struct { Street string `validate:"required"` City string `validate:"required"` Planet string `validate:"required"` Phone string `validate:"required"`}func main() { address := &Address{ Street: "Eavesdown Docks", Planet: "Persphone", Phone: "none", } user := &User{ FirstName: "Badger", LastName: "Smith", Age: 135, Email: "Badger.Smith@gmail.com", Addresses: []*Address{address}, } validate := validator.New() err := validate.Struct(user) if err != nil { fmt.Println("=== error msg ====") fmt.Println(err) if _, ok := err.(*validator.InvalidValidationError); ok { fmt.Println(err) return } fmt.Println("\r\n=========== error field info ====================") for _, err := range err.(validator.ValidationErrors) { // 列出效验出错字段的信息 fmt.Println("Namespace: ", err.Namespace()) fmt.Println("Fild: ", err.Field()) fmt.Println("StructNamespace: ", err.StructNamespace()) fmt.Println("StructField: ", err.StructField()) fmt.Println("Tag: ", err.Tag()) fmt.Println("ActualTag: ", err.ActualTag()) fmt.Println("Kind: ", err.Kind()) fmt.Println("Type: ", err.Type()) fmt.Println("Value: ", err.Value()) fmt.Println("Param: ", err.Param()) fmt.Println() } // from here you can create your own error messages in whatever language you wish return }}

运行 输出：

$ go run validation_struct.go
=== error msg ====
Key: 'User.Age' Error:Field validation for 'Age' failed on the 'lte' tag
Key: 'User.Addresses[0].City' Error:Field validation for 'City' failed on the 'required' tag

=========== error field info ====================
Namespace: User.Age
Fild: Age
StructNamespace: User.Age
StructField: Age
Tag: lte
ActualTag: lte
Kind: uint8
Type: uint8
Value: 135
Param: 130

Namespace: User.Addresses[0].City
Fild: City
StructNamespace: User.Addresses[0].City
StructField: City
Tag: required
ActualTag: required
Kind: string
Type: string
Value:
Param:

还可以给字段加一些其他tag信息，方面form，json的解析，如下：

type User struct { FirstName string `form:"firstname" json:"firstname" validate:"required"` LastName string `form:"lastname" json:"lastname" validate:"required"` Age uint8 ` form:"age" json:"age"validate:"gte=0,lte=130"` Email string ` form:"email" json:"email" validate:"required,email"`}

用户自定义函数验证

用户自定义函数验证字段是否合法，效验是否正确。

例子3: 通过字段tag自定义函数

validate.RegisterValidation

customer_tag.go：

package mainimport ( "fmt" "github.com/go-playground/validator/v10")type User struct { Name string `form:"name" json:"name" validate:"required,CustomerValidation"` //注意：required和CustomerValidation之间不能有空格，否则panic。CustomerValidation：自定义tag-函数标签 Age uint8 ` form:"age" json:"age" validate:"gte=0,lte=80"` //注意：gte=0和lte=80之间不能有空格，否则panic}var validate *validator.Validatefunc main() { validate = validator.New() validate.RegisterValidation("CustomerValidation", CustomerValidationFunc) //注册自定义函数，前一个参数是struct里tag自定义，后一个参数是自定义的函数 user := &User{ Name: "jimmy", Age: 86, } fmt.Println("first value: ", user) err := validate.Struct(user) if err != nil { fmt.Printf("Err(s):\n%+v\n", err) } user.Name = "tom" user.Age = 29 fmt.Println("second value: ", user) err = validate.Struct(user) if err != nil { fmt.Printf("Err(s):\n%+v\n", err) }}// 自定义函数func CustomerValidationFunc(f1 validator.FieldLevel) bool { // f1 包含了字段相关信息 // f1.Field() 获取当前字段信息 // f1.Param() 获取tag对应的参数 // f1.FieldName() 获取字段名称 return f1.Field().String() == "jimmy"}

运行输出：

$ go run customer.go
first value: &{jimmy 86}
Err(s):
Key: 'User.Age' Error:Field validation for 'Age' failed on the 'lte' tag
second value: &{tom 29}
Err(s):
Key: 'User.Name' Error:Field validation for 'Name' failed on the 'CustomerValidation' tag

**注意：

上面代码user struct定义中 ，validate里的required和CustomerValidation之间不能有空格，否则运行时报panic错误：panic: Undefined validation function ' CustomerValidation' on field 'Name'

例子4：自定义函数-直接注册函数1

不通过字段tag自定义函数，直接注册函数。

RegisterStructValidation

https://github.com/go-playground/validator/blob/master/_examples/struct-level/main.go

customer1.go

package mainimport ( "fmt" "github.com/go-playground/validator/v10")type User struct { FirstName string `json:firstname` LastName string `json:lastname` Age uint8 `validate:"gte=0,lte=130"` Email string `validate:"required,email"` FavouriteColor string `validate:"hexcolor|rgb|rgba"`}var validate *validator.Validatefunc main() { validate = validator.New() validate.RegisterStructValidation(UserStructLevelValidation, User{}) user := &User{ FirstName: "", LastName: "", Age: 30, Email: "TestFunc@126.com", FavouriteColor: "#000", } err := validate.Struct(user) if err != nil { fmt.Println(err) }}func UserStructLevelValidation(sl validator.StructLevel) { user := sl.Current().Interface().(User) if len(user.FirstName) == 0 && len(user.LastName) == 0 { sl.ReportError(user.FirstName, "FirstName", "firstname", "firstname", "") sl.ReportError(user.LastName, "LastName", "lastname", "lastname", "") }}

运行输出：

$ go run customer1.go
Key: 'User.FirstName' Error:Field validation for 'FirstName' failed on the 'firstname' tag
Key: 'User.LastName' Error:Field validation for 'LastName' failed on the 'lastname' tag

例子5：自定义函数-直接注册函数2

RegisterCustomTypeFunc

https://github.com/go-playground/validator/blob/master/_examples/custom/main.go

validate.RegisterCustomTypeFunc：验证类型的自定义函数

customer2.go：

package mainimport ( "database/sql" "database/sql/driver" "fmt" "reflect" "github.com/go-playground/validator/v10")type DbBackedUser struct { Name sql.NullString `validate:"required"` Age sql.NullInt64 `validate:"required"`}var validate *validator.Validatefunc main() { validate = validator.New() validate.RegisterCustomTypeFunc(ValidateValuer, sql.NullString{}, sql.NullInt64{}, sql.NullBool{}, sql.NullFloat64{}) // build object for validation x := DbBackedUser{Name: sql.NullString{String: "", Valid: true}, Age: sql.NullInt64{Int64: 0, Valid: false}} err := validate.Struct(x) if err != nil { fmt.Printf("Err(s):\n%+v\n", err) }}func ValidateValuer(field reflect.Value) interface{} { if valuer, ok := field.Interface().(driver.Valuer); ok { val, err := valuer.Value() if err == nil { return val } // handle the error how you want } return nil}

运行输出：

$ go run customer.go
Err(s):
Key: 'DbBackedUser.Name' Error:Field validation for 'Name' failed on the 'required' tag
Key: 'DbBackedUser.Age' Error:Field validation for 'Age' failed on the 'required' tag

注意，这个函数：
RegisterCustomTypeFunc，它上面有2行注释：

// RegisterCustomTypeFunc registers a CustomTypeFunc against a number of types
//
// NOTE: this method is not thread-safe it is intended that these all be registered prior to any validation

它是一个验证数据类型自定义函数，NOTE:这个方法不是线程安全的

五、参考

https://github.com/go-playground/validator/blob/master/README.mdhttps://github.com/go-playground/validator/tree/master/_examples

总结

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