MinLength static method

String? Function(String? value)? MinLength({ required int length, String errorMessage = 'Minimum length is *min_len*', String? next(String value)?, })

Returns a validator that checks if a string is at least a certain length.

Arguments :

• length : The minimum length of the string.
• errorMessage : The error message to return if the string is not at least a certain length.
• next : A validator to run after this validator.

Usage :

TextFormField(
validator: Validators.MinLength(length: 5),
),

Implementation

static String? Function(String? value)? MinLength({
  required int length,
  String errorMessage = 'Minimum length is *min_len*',
  String? Function(String value)? next,
}) {
  if (errorMessage.contains('*min_len*')) {
    errorMessage = errorMessage.replaceAll('*min_len*', length.toString());
  }
  return (value) {
    if (value == null || value.trim().isEmpty) {
      return null;
    }

    if (value.length < length) {
      return errorMessage;
    }

    if (next != null) {
      return next(value);
    }

    return null;
  };
}