lengthValidator function

String? lengthValidator(
  1. String value, {
  2. int? min,
  3. int? max,
})

Validates the length of the input value based on minimum and maximum constraints.

Implementation

String? lengthValidator(String value, {int? min, int? max}) {
  final length = value.trim().length;
  if (min != null && length < min) {
    return 'The value must be at least $min characters.';
  }
  if (max != null && length > max) {
    return 'The value must be at most $max characters.';
  }
  return null;
}