form_guard 0.0.1

A lightweight and customizable Dart form validation package for email, passwords, required fields, length checks, matching values, and more.

Form Guard

A lightweight and customizable form validation package for Dart and Flutter.

form_guard provides simple, reusable validators for common form fields such as email addresses, passwords, required fields, string lengths, and matching values.

Features

• Required field validation
• Email validation
• Password validation
• Minimum length validation
• Maximum length validation
• Matching field validation
• Custom validation messages
• Works with Dart and Flutter
• Lightweight with no unnecessary dependencies

Installation

Add form_guard to your pubspec.yaml:

dependencies:
  form_guard: ^0.0.1

Then run:

dart pub get

For Flutter projects, you can use:

flutter pub get

Import

import 'package:form_guard/form_guard.dart';

Usage

Required Field

final result = FormGuard.required('');

print(result);
// This field is required.

A valid value returns null:

final result = FormGuard.required('Jorj');

print(result);
// null

Email

final result = FormGuard.email('[e-mail]');

print(result);
// null

Invalid email:

final result = FormGuard.email('invalid-email');

print(result);
// Please enter a valid email address.

Password

final result = FormGuard.password(
  'Hello123',
  minLength: 8,
  requireUppercase: true,
  requireLowercase: true,
  requireNumber: true,
);

print(result);
// null

You can also require a special character:

final result = FormGuard.password(
  'Hello123!',
  requireSpecialCharacter: true,
);

Minimum Length

final result = FormGuard.minLength('hello', 8);

print(result);
// Must be at least 8 characters.

Maximum Length

final result = FormGuard.maxLength('Hello World', 5);

print(result);
// Must not exceed 5 characters.

Matching Values

Useful for fields such as password confirmation:

final password = 'Hello123';
final confirmPassword = 'Hello123';

final result = FormGuard.matches(
  confirmPassword,
  password,
);

print(result);
// null

Custom Error Messages

All validators support customizable error messages.

FormGuard.required(
  '',
  message: 'Please enter your name.',
);

For example:

FormGuard.email(
  'invalid',
  message: 'That email address does not look right.',
);

Flutter

form_guard works directly with Flutter's TextFormField.

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

For configurable validators:

TextFormField(
  obscureText: true,
  decoration: const InputDecoration(
    labelText: 'Password',
  ),
  validator: (value) {
    return FormGuard.password(
      value,
      minLength: 8,
      requireUppercase: true,
      requireNumber: true,
    );
  },
);

Complete Example

import 'package:form_guard/form_guard.dart';

void main() {
  final email = '[e-mail]';
  final password = 'Hello123';
  final confirmPassword = 'Hello123';

  print('Email: ${FormGuard.email(email)}');
  print('Password: ${FormGuard.password(password)}');
  print(
    'Passwords match: '
    '${FormGuard.matches(confirmPassword, password)}',
  );

  final invalidEmail = 'test';

  print('Invalid email: ${FormGuard.email(invalidEmail)}');
}

In form_guard, validators follow the standard Flutter validation convention:

• null means the value is valid.
• A String means validation failed and contains the error message.

Contributing

Contributions, bug reports, and feature requests are welcome.

If you find an issue or have an idea for a new validator, feel free to open an issue or submit a pull request on GitHub.

License

Form Guard is available under the MIT License. See the LICENSE file for more information.