validation

var Base64 = validation.By(func(value interface{}) error {
	s, ok := value.(string)
	if !ok {
		return validation.NewError("validation_base64_type", "must be a string")
	}
	if s == "" {
		return nil
	}
	_, err := base64.StdEncoding.DecodeString(s)
	if err != nil {
		return validation.NewError("validation_base64", "must be valid base64-encoded data")
	}
	return nil
})

var NotBlank = validation.NewStringRuleWithError(
	func(s string) bool {
		return strings.TrimSpace(s) != ""
	},
	validation.NewError("validation_not_blank", "must not be blank"),
)