validator-sample.go

package main

import (
	"fmt"

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

type Foo struct {
	// ID string `validate:"alphanum,len=3|len=5,excludesall=abcdefghijklmnopgrstuvwxyz"`
	ID string `validate:"id"`
}

func main() {

	validate := validator.New()
	validate.RegisterAlias("id", "alphanum,len=3|len=5,excludesall=abcdefghijklmnopgrstuvwxyz")
	foo := &Foo{"1ABc2"}
	err := validate.Struct(foo)
	if err == nil {
		panic("expects err is NOT nil")
	}

	_, ok := err.(*validator.InvalidValidationError)
	if ok {
		panic("expects ok is false")
	}

	for _, err := range err.(validator.ValidationErrors) {
		fmt.Println(err.Namespace())
		fmt.Println(err.Field())
		fmt.Println(err.StructNamespace())
		fmt.Println(err.StructField())
		fmt.Println(err.Tag())
		fmt.Println(err.ActualTag())
		fmt.Println(err.Kind())
		fmt.Println(err.Type())
		fmt.Println(err.Value())
		fmt.Println(err.Param())
		fmt.Println()
	}

	foo = &Foo{"1ABC2"}
	err = validate.Struct(foo)
	if err != nil {
		panic(err)
	}
}