validate/length.go

package validate

import "unicode/utf8"

var (
	ErrMustBeLonger  = NewError("must contain at least %d characters")
	ErrMustBeShorter = NewError("must contain no more than %d characters")
)

// MaxLength validates that a string is no longer than a given maximum.
// Length is counted in runes, so multi-byte characters count as one.
func MaxLength(l int) func(string) error {
	return func(value string) error {
		if utf8.RuneCountInString(value) > l {
			return ErrMustBeShorter.With(l)
		}
		return nil
	}
}

// MinLength validates that a string is at least a given minimum length.
// Length is counted in runes, so multi-byte characters count as one.
func MinLength(l int) func(string) error {
	return func(value string) error {
		if utf8.RuneCountInString(value) < l {
			return ErrMustBeLonger.With(l)
		}
		return nil
	}
}