package validator import ( "slices" "strings" "unicode/utf8" ) type Validator struct { FieldErrors map[string]string } func (v *Validator) Valid() bool { return len(v.FieldErrors) == 0 } func (v *Validator) AddFieldError(key, message string) { if v.FieldErrors == nil { v.FieldErrors = make(map[string]string) } if _, exists := v.FieldErrors[key]; !exists { v.FieldErrors[key] = message } } func (v *Validator) CheckField(ok bool, key, message string) { if !ok { v.AddFieldError(key, message) } } func NotBlank(value string) bool { return strings.TrimSpace(value) != "" } func MaxChars(value string, n int) bool { return utf8.RuneCountInString(value) <= n } func PermittedValue[T comparable](value T, permittedValues ...T) bool { return slices.Contains(permittedValues, value) }