go get gopkg.in/go-playground/validator.v9

package main

import (
 "fmt"
 "gopkg.in/go-playground/validator.v9"
)

// User contains user information
type UserInfo struct {
 FirstName  string  `validate:"required"`
 LastName  string  `validate:"required"`
 Age   uint8  `validate:"gte=0,lte=100"`
 Email   string  `validate:"required,email"`
}


func main() {
 validate := validator.New()
 user := &UserInfo{
  FirstName:  "Badger",
  LastName:  "Smith",
  Age:   105,
  Email:   "",
 }
 err := validate.Struct(user)
 if err != nil {
  for _, err := range err.(validator.ValidationErrors) {
   fmt.Println(err)
  }
  return
 }
 fmt.Println("success")
}

1.IP
type UserInfo struct {
 Ip    string  `validate:"ip"`
}
2.数字
type UserInfo struct {
 Number float32 `validate:"numeric"`
}
3.最大值
type UserInfo struct {
 Number float32 `validate:"max=10"`
}
4.最小值
type UserInfo struct {
 Number float32 `validate:"min=10"`
}

package main

import (
 "fmt"
 "gopkg.in/go-playground/validator.v9"
 "unicode/utf8"
)

// User contains user information
type UserInfo struct {
 Name   string  `validate:"checkName"`
 Number float32 `validate:"numeric"`
}
// 自定义验证函数
func checkName(fl validator.FieldLevel) bool {
 count := utf8.RuneCountInString(fl.Field().String())
 fmt.Printf("length: %v \n", count)
 if count > 5 {
  return false
 }
 return true
}

func main() {
 validate := validator.New()
  //注册自定义函数，与struct tag关联起来
 err := validate.RegisterValidation("checkName", checkName)
 user := &UserInfo{
  Name:   "我是中国人，我爱自己的祖国",
  Number:   23,
 }
 err = validate.Struct(user)
 if err != nil {
  for _, err := range err.(validator.ValidationErrors) {
   fmt.Println(err)
  }
  return
 }
 fmt.Println("success")
}