fix(validation): correct CustomValidator and strutils.Parser handling, add tests

internal/serialization/validation.go

@@ -1,6 +1,8 @@
 package serialization
 
 import (
+	"reflect"
+
 	"github.com/go-playground/validator/v10"
 	gperr "github.com/yusing/goutils/errs"
 )
@@ -9,10 +11,6 @@ var validate = validator.New()
 
 var ErrValidationError = gperr.New("validation error")
 
-type CustomValidator interface {
-	Validate() gperr.Error
-}
-
 func Validator() *validator.Validate {
 	return validate
 }
@@ -23,3 +21,40 @@ func MustRegisterValidation(tag string, fn validator.Func) {
 		panic(err)
 	}
 }
+
+type CustomValidator interface {
+	Validate() gperr.Error
+}
+
+var validatorType = reflect.TypeFor[CustomValidator]()
+
+func ValidateWithCustomValidator(v reflect.Value) gperr.Error {
+	if v.Kind() == reflect.Pointer {
+		if v.IsNil() {
+			// return nil
+			return validateWithValidator(reflect.New(v.Type().Elem()))
+		}
+		if v.Type().Implements(validatorType) {
+			return v.Interface().(CustomValidator).Validate()
+		}
+		return validateWithValidator(v.Elem())
+	} else {
+		vt := v.Type()
+		if vt.PkgPath() != "" { // not a builtin type
+			if vt.Implements(validatorType) {
+				return v.Interface().(CustomValidator).Validate()
+			}
+			if v.CanAddr() {
+				return validateWithValidator(v.Addr())
+			}
+		}
+	}
+	return nil
+}
+
+func validateWithValidator(v reflect.Value) gperr.Error {
+	if v.Type().Implements(validatorType) {
+		return v.Interface().(CustomValidator).Validate()
+	}
+	return nil
+}