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 boolerr := 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('rnEnd!!') }
运行输出：
go run simple1.goKey: ’’ Error:Field validation for ’’ failed on the ’required’ tagKey: ’’ Error:Field validation for ’’ failed on the ’required’ tagsuccessKey: ’’ 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('rn=========== 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 wishreturn}}
运行 输出：
$ go run validation_struct.go=== error msg ====Key: ’User.Age’ Error:Field validation for ’Age’ failed on the ’lte’ tagKey: ’User.Addresses[0].City’ Error:Field validation for ’City’ failed on the ’required’ tag
=========== error field info ====================Namespace: User.AgeFild: AgeStructNamespace: User.AgeStructField: AgeTag: lteActualTag: lteKind: uint8Type: uint8Value: 135Param: 130
Namespace: User.Addresses[0].CityFild: CityStructNamespace: User.Addresses[0].CityStructField: CityTag: requiredActualTag: requiredKind: stringType: stringValue: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%+vn', err)}user.Name = 'tom'user.Age = 29fmt.Println('second value: ', user)err = validate.Struct(user)if err != nil {fmt.Printf('Err(s):n%+vn', 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.gofirst value: &{jimmy 86}Err(s):Key: ’User.Age’ Error:Field validation for ’Age’ failed on the ’lte’ tagsecond 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.goKey: ’User.FirstName’ Error:Field validation for ’FirstName’ failed on the ’firstname’ tagKey: ’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 validationx := 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%+vn', 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.goErr(s):Key: ’DbBackedUser.Name’ Error:Field validation for ’Name’ failed on the ’required’ tagKey: ’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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