pattern static method

String? pattern(
  1. String? value,
  2. RegExp pattern, {
  3. String? message,
})

Validates that the value matches a pattern

Example:

Validators.pattern(value, RegExp(r'^[A-Z]+$'));

Implementation

static String? pattern(String? value, RegExp pattern, {String? message}) {
  if (value == null || value.isEmpty) return null;
  if (!pattern.hasMatch(value)) {
    return message ?? 'Invalid format';
  }
  return null;
}