Validation

การ validate input data ใน Go applications

Basic Validation

package main

import (
    "errors"
    "fmt"
    "regexp"
    "strings"
)

type User struct {
    Name     string
    Email    string
    Age      int
    Password string
}

func (u *User) Validate() error {
    if strings.TrimSpace(u.Name) == "" {
        return errors.New("name is required")
    }

    if len(u.Name) < 2 || len(u.Name) > 50 {
        return errors.New("name must be 2-50 characters")
    }

    if !isValidEmail(u.Email) {
        return errors.New("invalid email format")
    }

    if u.Age < 0 || u.Age > 150 {
        return errors.New("age must be 0-150")
    }

    if len(u.Password) < 8 {
        return errors.New("password must be at least 8 characters")
    }

    return nil
}

func isValidEmail(email string) bool {
    pattern := `^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$`
    matched, _ := regexp.MatchString(pattern, email)
    return matched
}

func main() {
    user := User{
        Name:     "Alice",
        Email:    "alice@example.com",
        Age:      30,
        Password: "password123",
    }

    if err := user.Validate(); err != nil {
        fmt.Println("Validation error:", err)
        return
    }

    fmt.Println("User is valid")
}