GolangのValidationチェック(go-playground編)

#初めに
GolangでのValidationチェックを実施する記事です。

#サンプルコード

main.go

package main

import (
	"fmt"

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

// User contains user information
type User struct {
	FirstName      string     `validate:"required"`
	LastName       string     `validate:"required"`
	Age            uint8      `validate:"gte=0,lte=130"`
	Email          string     `validate:"required,email"`
	FavouriteColor string     `validate:"iscolor"`                // alias for 'hexcolor|rgb|rgba|hsl|hsla'
	Addresses      []*Address `validate:"required,dive,required"` // a person can have a home and cottage...
}

// Address houses a users address information
type Address struct {
	Street string `validate:"required"`
	City   string `validate:"required"`
	Planet string `validate:"required"`
	Phone  string `validate:"required"`
}

// use a single instance of Validate, it caches struct info
var validate *validator.Validate

func main() {

	validate = validator.New()

	validateStruct()
	validateVariable()
}

func validateStruct() {

	address := &Address{
		Street: "Eavesdown Docks",
		Planet: "Persphone",
		Phone:  "none",
	}

	user := &User{
		FirstName:      "Badger",
		LastName:       "Smith",
		Age:            135,
		Email:          "[e-mail]",
		FavouriteColor: "#000-",
		Addresses:      []*Address{address},
	}

	err := validate.Struct(user)
	if err != nil {

		if _, ok := err.(*validator.InvalidValidationError); ok {
			fmt.Println(err)
			return
		}

		for _, err := range err.(validator.ValidationErrors) {
			fmt.Println("=====================【validateチェック】===========================")
			fmt.Println("1: " + err.Namespace())
			fmt.Println("2: " + err.Field())
			fmt.Println("3: " + err.StructNamespace())
			fmt.Println("4: " + err.StructField())
			fmt.Println("5: " + err.Tag())
			fmt.Println("6: " + err.ActualTag())
			fmt.Println(err.Kind())
			fmt.Println(err.Type())
			fmt.Println(err.Value())
			fmt.Println("10" + err.Param())
		}
		fmt.Println("====================================================================")

		// from here you can create your own error messages in whatever language you wish
		return
	}

	// save user to database
}

func validateVariable() {

	myEmail := "joeybloggs.gmail.com"

	errs := validate.Var(myEmail, "required,email")

	if errs != nil {
		fmt.Println(errs) // output: Key: "" Error:Field validation for "" failed on the "email" tag
		return
	}

	// email ok, move on
}

○実行結果

main.go

=====================【validateチェック】===========================
1: User.Addresses[0].City
2: City
3: User.Addresses[0].City
4: City
5: required
6: required
string
string

10
====================================================================
Key: '' Error:Field validation for '' failed on the 'email' tag

うーん、なかなか分かりづらいですね。。。
下記、URLがわかりやすかったので、乗っけておきます。

○追記
ozzo-validationチェックが使いやすかったので、こっちおすすめです。mattnさんの記事を乗っけておきます！！！
https://zenn.dev/mattn/articles/893f28eff96129

→さっくさく作れるので楽しいですね！！！

○参考文献