zeba_academy_form_rules #

A lightweight, reusable, dependency-free form validation rules package for Dart and Flutter applications.

zeba_academy_form_rules provides composable validation rules for common form requirements such as required fields, email addresses, string length, numeric values, passwords, matching fields, and custom validation logic.

✨ Features #

• ✅ Required field validation
• 📧 Email validation
• 📏 Minimum length validation
• 📐 Maximum length validation
• 🔢 Numeric validation
• 🔐 Configurable password validation
• 🔁 Matching field validation
• 🧩 Custom validation rules
• 🧱 Composable validation rules
• ❌ Multiple validation errors
• 💬 Custom error messages
• ⚡ Synchronous validation
• 🪶 Lightweight and dependency-free
• 🎯 Works with Flutter TextFormField
• 🧪 Unit-test friendly
• 📦 Simple public API

📦 Installation #

Add the package to your pubspec.yaml:

dependencies:
  zeba_academy_form_rules: ^0.0.1

Then run:

flutter pub get

Or:

dart pub add zeba_academy_form_rules

🚀 Getting Started #

Import the package:

import 'package:zeba_academy_form_rules/zeba_academy_form_rules.dart';

Create a validation rule:

const rule = RequiredRule();

final result = rule.validate('Hello');

print(result.isValid); // true

For invalid values:

const rule = RequiredRule();

final result = rule.validate('');

print(result.isValid); // false
print(result.firstError); // This field is required.

🧩 Available Rules #

RequiredRule #

Validates that a string is not null, empty, or whitespace-only.

const rule = RequiredRule();

rule.isValid('Flutter'); // true
rule.isValid(''); // false
rule.isValid('   '); // false

Custom Error Message #

const rule = RequiredRule(
  message: 'Please enter your name.',
);

📧 EmailRule #

Validates email addresses.

const rule = EmailRule();

rule.isValid('user@example.com'); // true
rule.isValid('invalid-email'); // false

Custom message:

const rule = EmailRule(
  message: 'Please enter a valid email.',
);

EmailRule allows empty values so it can be composed with RequiredRule.

final validator = RuleValidator<String>(
  [
    RequiredRule(),
    EmailRule(),
  ],
);

📏 MinLengthRule #

Validates the minimum number of characters.

const rule = MinLengthRule(8);

rule.isValid('Flutter'); // false
rule.isValid('Flutter!'); // true

Custom message:

const rule = MinLengthRule(
  8,
  message: 'Password must contain at least 8 characters.',
);

📐 MaxLengthRule #

Validates the maximum number of characters.

const rule = MaxLengthRule(20);

rule.isValid('Flutter'); // true
rule.isValid('This value is too long for the field'); // false

Custom message:

const rule = MaxLengthRule(
  20,
  message: 'Username cannot exceed 20 characters.',
);

🔢 NumericRule #

Validates that a value contains only digits.

const rule = NumericRule();

rule.isValid('123456'); // true
rule.isValid('123abc'); // false

Custom message:

const rule = NumericRule(
  message: 'Please enter numbers only.',
);

🔐 PasswordRule #

Provides configurable password validation.

By default, it checks:

• Minimum 8 characters
• At least one uppercase letter
• At least one lowercase letter
• At least one number
• At least one special character

const rule = PasswordRule();

final result = rule.validate('Password@123');

print(result.isValid); // true

Weak Password #

const rule = PasswordRule();

final result = rule.validate('abc');

print(result.isValid); // false
print(result.errors);

A password can return multiple validation errors.

Custom Password Requirements #

const rule = PasswordRule(
  minLength: 10,
  requireUppercase: true,
  requireLowercase: true,
  requireDigit: true,
  requireSpecialCharacter: false,
);

This allows you to adapt the rule to different application requirements.

🔁 MatchRule #

Validates that two values are equal.

This is useful for:

• Confirm password
• Confirm email
• Repeat phone number
• Confirmation fields

Example:

const rule = MatchRule<String>(
  otherValue: 'Password@123',
  message: 'Passwords do not match.',
);

rule.isValid('Password@123'); // true
rule.isValid('Password@456'); // false

🧩 CustomRule #

Create your own validation logic without creating a new class.

final rule = CustomRule<String>(
  validator: (value) {
    return value != null && value.startsWith('Zeba');
  },
  message: 'Value must start with Zeba.',
);

rule.isValid('Zeba Academy'); // true
rule.isValid('Flutter'); // false

This makes the package extensible without requiring changes to the package itself.

🧱 Combining Multiple Rules #

Use RuleValidator when a field requires multiple rules.

For example, username validation:

final usernameValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Username is required.',
    ),
    MinLengthRule(
      3,
      message: 'Username must contain at least 3 characters.',
    ),
    MaxLengthRule(
      20,
      message: 'Username cannot exceed 20 characters.',
    ),
  ],
);

Validate:

final result = usernameValidator.validate('ab');

print(result.isValid); // false
print(result.errors);

First Error #

If you only need the first error:

final error = usernameValidator.error('ab');

print(error);

Check Validity #

final isValid = usernameValidator.isValid('sarvesh');

print(isValid);

📋 Multiple Validation Errors #

RuleValidator executes all supplied rules and collects their errors.

final validator = RuleValidator<String>(
  [
    RequiredRule(),
    MinLengthRule(8),
    MaxLengthRule(20),
  ],
);

final result = validator.validate('abc');

print(result.errors);

This makes it possible to display all applicable validation problems instead of stopping after the first rule.

📱 Flutter Integration #

The package is framework-independent in its validation logic and can be used directly with Flutter forms.

Example:

final emailValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Email is required.',
    ),
    EmailRule(
      message: 'Enter a valid email address.',
    ),
  ],
);

Use it with TextFormField:

TextFormField(
  validator: (value) {
    return emailValidator.error(value);
  },
)

This keeps validation logic separate from the widget layer.

🔐 Complete Login Form Example #

import 'package:flutter/material.dart';
import 'package:zeba_academy_form_rules/zeba_academy_form_rules.dart';

class LoginForm extends StatelessWidget {
  LoginForm({super.key});

  final emailValidator = RuleValidator<String>(
    [
      RequiredRule(
        message: 'Email is required.',
      ),
      EmailRule(
        message: 'Enter a valid email address.',
      ),
    ],
  );

  final passwordValidator = RuleValidator<String>(
    [
      RequiredRule(
        message: 'Password is required.',
      ),
      PasswordRule(),
    ],
  );

  @override
  Widget build(BuildContext context) {
    return Form(
      child: Column(
        children: [
          TextFormField(
            keyboardType: TextInputType.emailAddress,
            validator: emailValidator.error,
          ),
          TextFormField(
            obscureText: true,
            validator: passwordValidator.error,
          ),
        ],
      ),
    );
  }
}

📱 Registration Form Example #

final usernameValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Username is required.',
    ),
    MinLengthRule(
      3,
      message: 'Username must contain at least 3 characters.',
    ),
    MaxLengthRule(
      20,
      message: 'Username cannot exceed 20 characters.',
    ),
  ],
);

final emailValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Email is required.',
    ),
    EmailRule(),
  ],
);

final passwordValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Password is required.',
    ),
    PasswordRule(),
  ],
);

📞 Phone Number Example #

final phoneValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Phone number is required.',
    ),
    NumericRule(
      message: 'Phone number must contain only digits.',
    ),
    MinLengthRule(
      10,
      message: 'Phone number must contain 10 digits.',
    ),
    MaxLengthRule(
      10,
      message: 'Phone number must contain 10 digits.',
    ),
  ],
);

🔑 Confirm Password Example #

final password = passwordController.text;

final confirmPasswordValidator = RuleValidator<String>(
  [
    RequiredRule(
      message: 'Please confirm your password.',
    ),
    MatchRule<String>(
      otherValue: password,
      message: 'Passwords do not match.',
    ),
  ],
);

Then:

TextFormField(
  controller: confirmPasswordController,
  obscureText: true,
  validator: confirmPasswordValidator.error,
)

🎨 Custom Validation Example #

You can implement application-specific rules without modifying the package.

final usernameRule = CustomRule<String>(
  validator: (value) {
    if (value == null) {
      return false;
    }

    return RegExp(r'^[a-zA-Z0-9_]+$').hasMatch(value);
  },
  message: 'Only letters, numbers and underscores are allowed.',
);

Combine it with built-in rules:

final validator = RuleValidator<String>(
  [
    RequiredRule(),
    MinLengthRule(3),
    MaxLengthRule(20),
    usernameRule,
  ],
);

🧪 Testing #

The package is designed to be easily testable.

Run the test suite:

flutter test

Run static analysis:

flutter analyze

Format the source:

dart format lib test

Check package publishing:

flutter pub publish --dry-run

📂 Project Structure #

zeba_academy_form_rules/
│
├── lib/
│   ├── zeba_academy_form_rules.dart
│   └── src/
│       ├── custom_rule.dart
│       ├── email_rule.dart
│       ├── form_rule.dart
│       ├── length_rules.dart
│       ├── match_rule.dart
│       ├── numeric_rule.dart
│       ├── password_rule.dart
│       ├── required_rule.dart
│       ├── rule_validator.dart
│       └── validation_result.dart
│
├── test/
│   ├── form_rule_test.dart
│   └── validation_result_test.dart
│
├── CHANGELOG.md
├── LICENSE
├── README.md
└── pubspec.yaml

🎯 Design Goals #

zeba_academy_form_rules is designed around a few simple principles:

Simple #

Validation should be easy to understand and use.

Reusable #

Rules should work across different screens and applications.

Composable #

Multiple rules can be combined for complex validation requirements.

Dependency-Free #

The package avoids unnecessary runtime dependencies.

Testable #

Every validation rule can be tested independently.

Flutter-Friendly #

The package integrates naturally with Flutter's Form and TextFormField.

📋 API Overview #

💡 Why Use This Package? #

Instead of writing validation logic repeatedly:

if (email.isEmpty) {
  // ...
}

if (!email.contains('@')) {
  // ...
}

if (password.length < 8) {
  // ...
}

You can define reusable rules:

final emailValidator = RuleValidator<String>(
  [
    RequiredRule(),
    EmailRule(),
  ],
);

And reuse them throughout your application.

🤝 Contributing #

Contributions are welcome!

If you find a bug, have an improvement, or want to suggest a new validation rule:

1. Fork the repository.
2. Create a feature branch.
3. Make your changes.
4. Add or update tests.
5. Run dart format lib test.
6. Run flutter analyze.
7. Run flutter test.
8. Submit a pull request.

Please keep contributions focused, documented, and tested.

📄 License #

This project is licensed under the GNU General Public License v3.0 (GPL-3.0).

You should include the complete GPL-3.0 license text in the project's LICENSE file.

See the official GNU GPL documentation for more information.

👨‍💻 About Me #

✨ I’m Sufyan bin Uzayr, an open-source developer passionate about building and sharing meaningful projects.

You can learn more about me and my work at sufyanism.com or connect with me on LinkedIn.

🎓 Zeba Academy #

Your all-in-one learning hub! #

🚀 Explore courses and resources in coding, tech, and development at zeba.academy and code.zeba.academy.

Empower yourself with practical skills through curated tutorials, real-world projects, and hands-on experience. Level up your tech game today! 💻✨

Zeba Academy is a learning platform dedicated to coding, technology, and development.

➡ Visit our main site: zeba.academy

➡ Explore hands-on courses and resources at: code.zeba.academy

➡ Check out our YouTube for more tutorials: zeba.academy

➡ Follow us on Instagram: zeba.academy

⭐ Support the Project #

If zeba_academy_form_rules helps you build better Flutter applications:

• ⭐ Star the repository
• 📦 Like the package on pub.flutter-io.cn
• 🐛 Report issues
• 💡 Suggest improvements
• 🤝 Contribute to the project
• 📢 Share it with other Flutter developers

Every contribution helps improve the project and the wider Flutter community.

Thank you for visiting and supporting Zeba Academy! 💙

Happy coding! 🚀