indo_form_validator

A lightweight form validation library for Indonesian applications. Provides validators for phone numbers, NIK, NPWP, and email with bilingual error messages.

Features

• Phone number validation (Indonesian formats: 08xx, +62, 62)
• NIK validation (16 digits with optional region code checking)
• NPWP validation (15 digits with formatting support)
• Email validation (RFC 5322 compliant)
• Bilingual error messages (Indonesian and English)
• Validator chaining and custom validators
• Strict validation mode
• Null-safe and zero dependencies
• Direct Flutter Form integration

Installation

Add to your pubspec.yaml:

dependencies:
  indo_form_validator: ^1.0.0

Then run:

flutter pub get

Usage

Basic Form Validation

import 'package:indo_form_validator/indo_form_validator.dart';

TextFormField(
  decoration: const InputDecoration(labelText: 'Phone Number'),
  validator: IndoValidator.phone(),
)

TextFormField(
  decoration: const InputDecoration(labelText: 'NIK'),
  validator: IndoValidator.nik(),
)

TextFormField(
  decoration: const InputDecoration(labelText: 'NPWP'),
  validator: IndoValidator.npwp(),
)

TextFormField(
  decoration: const InputDecoration(labelText: 'Email'),
  validator: IndoValidator.email(),
)

English Error Messages

TextFormField(
  validator: IndoValidator.phone(
    config: ValidationConfig.english,
  ),
)

Strict Validation Mode

// NIK with region code validation
TextFormField(
  validator: IndoValidator.nik(
    config: ValidationConfig.strictMode,
    validateRegion: true,
  ),
)

// NPWP with format validation
TextFormField(
  validator: IndoValidator.npwp(
    config: ValidationConfig.strictMode,
  ),
)

Validator Chaining

TextFormField(
  validator: IndoValidator.chain([
    IndoValidator.phone(),
    (value) {
      final cleaned = value?.replaceAll(RegExp(r'[\s\-]'), '');
      return cleaned?.length == 12 ? null : 'Must be 12 digits';
    },
  ]),
)

Custom Validators

TextFormField(
  validator: IndoValidator.custom(
    (value) => value?.startsWith('08') ?? false,
    'Phone must start with 08',
  ),
)

Standalone Validation

// Using ValidationResult
final result = IndoValidator.validatePhone('081234567890');
if (result.isValid) {
  print('Phone is valid');
} else {
  print('Error: ${result.message}');
}

// Using boolean check
if (PhoneValidator.isValid('081234567890')) {
  print('Valid phone number');
}

// Direct validation
final nikResult = NikValidator.validate('3201234567890123');
print(nikResult.isValid); // true or false
print(nikResult.message); // error message or null

NPWP Formatting

final formatted = NpwpValidator.format('123456789012345');
print(formatted); // 12.345.678.9-012.345

Validation Rules

Phone Number

• Supports formats: 08xxxxxxxxxx, +628xxxxxxxxxx, 628xxxxxxxxxx
• Length: 10-13 digits after prefix
• Automatically removes spaces, dashes, and parentheses

NIK (Nomor Induk Kependudukan)

• Exactly 16 digits
• Numeric only
• Optional region code validation (province: 11-94)
• Supports formatted input with spaces/dashes

NPWP (Nomor Pokok Wajib Pajak)

• Exactly 15 digits
• Numeric only
• Supports formatted (XX.XXX.XXX.X-XXX.XXX) and non-formatted input
• Strict mode validates format structure

Email

• RFC 5322 compliant regex
• Strict mode checks for consecutive dots and valid TLD length

API Reference

IndoValidator

Main validator class providing convenient access to all validators.

// Form validators (returns String? for FormField)
IndoValidator.phone({ValidationConfig config})
IndoValidator.nik({ValidationConfig config, bool validateRegion})
IndoValidator.npwp({ValidationConfig config})
IndoValidator.email({ValidationConfig config})

// Validation methods (returns ValidationResult)
IndoValidator.validatePhone(String? value, {ValidationConfig config})
IndoValidator.validateNik(String? value, {ValidationConfig config, bool validateRegion})
IndoValidator.validateNpwp(String? value, {ValidationConfig config})
IndoValidator.validateEmail(String? value, {ValidationConfig config})

// Utility methods
IndoValidator.chain(List<String? Function(String?)> validators)
IndoValidator.custom(bool Function(String?) validationFunction, String errorMessage)

Individual Validators

Each validator has three methods:

// Returns ValidationResult with isValid and message
PhoneValidator.validate(String? value, {ValidationConfig config})

// Returns String? for FormField.validator
PhoneValidator.validator({ValidationConfig config})

// Returns bool for quick checks
PhoneValidator.isValid(String? value)

ValidationConfig

const ValidationConfig({
  String language = 'id',  // 'id' or 'en'
  bool strict = false,
})

// Predefined configs
ValidationConfig.defaultConfig  // Indonesian, non-strict
ValidationConfig.english        // English, non-strict
ValidationConfig.strictMode     // Indonesian, strict

ValidationResult

class ValidationResult {
  final bool isValid;
  final String? message;
  
  const ValidationResult.valid();
  const ValidationResult.invalid(String message);
}

Complete Example

class MyForm extends StatefulWidget {
  @override
  State<MyForm> createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            decoration: const InputDecoration(labelText: 'Phone'),
            validator: IndoValidator.phone(),
          ),
          TextFormField(
            decoration: const InputDecoration(labelText: 'NIK'),
            validator: IndoValidator.nik(),
          ),
          TextFormField(
            decoration: const InputDecoration(labelText: 'NPWP'),
            validator: IndoValidator.npwp(),
          ),
          TextFormField(
            decoration: const InputDecoration(labelText: 'Email'),
            validator: IndoValidator.email(),
          ),
          ElevatedButton(
            onPressed: () {
              if (_formKey.currentState!.validate()) {
                // Form is valid
              }
            },
            child: const Text('Submit'),
          ),
        ],
      ),
    );
  }
}

Testing

Run tests:

flutter test

The package includes comprehensive unit tests covering valid and invalid inputs, edge cases, error messages in both languages, and strict mode validation.

Contributing

Contributions are welcome. Please read CONTRIBUTING.md for details.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Changelog

See CHANGELOG.md for a list of changes.