i_validator

A Flutter package offering robust validation utilities for forms, inputs, and business logic. Includes predefined validators for strings, numbers, dates, lists, and custom regex patterns with type-safe generic support.

Features

📜 Core Validators

• IValidator<T> – Generic interface for all validators (supports any input type).
• RequiredFieldValidator<T> – Ensures non-null/non-empty values for any type.
• RequiredStringValidator – Non-empty text validation.
• RequiredTrueValidator – Boolean true validation (e.g., for checkboxes).
• RequiredListValidator – Validates non-empty lists.
• RequiredDateValidator – Ensures a date is provided.

🔢 Numeric Validators

• MinValueValidator<T extends num> – Checks minimum value (int/double).
• MaxValueValidator<T extends num> – Checks maximum value (int/double).

📝 Text Validators

• EmailValidator – RFC-compliant email format validation.
• PasswordValidator – Configurable strength levels (easy, medium, strong).
• MinLengthValidator – Enforces minimum string length.
• RegexValidator – Custom regex pattern validation (e.g., URLs, usernames).
• PhoneNumberValidator – Global phone number format support.

🔐 Security Validators

• OtpValidator – Validates OTP codes (custom length).
• PinNumberValidator – 4 or 6-digit PIN validation.
• ConfirmPasswordValidator – Compares two password fields.

📂 File Validation

• File type validation – Checks image formats (e.g., PNG, JPEG) via extensions.

🚀 Installation

Add to pubspec.yaml:

dependencies:
  i_validator: <latest_version>

Run:

flutter pub get

🛠 Usage

1. Email Validation

final error = EmailValidator().validate("invalid-email");  
print(error); // "Enter a valid email"  

2. Password Validation (Strong)

final validator = PasswordValidator(  
  minLength: 8,  
  strength: PasswordStrength.strong, // Requires uppercase, number, symbol  
);  
print(validator.validate("weak")); // "Password must be at least 8 characters"  

3. OTP Validation (6-digit)

final error = OtpValidator(length: 6).validate("123");  
print(error); // "OTP must be 6 digits"  

4. Required Field Validation

final error = RequiredFieldValidator<String>().validate("");  
print(error); // "This field is required"  

5. Custom Regex Validation

final validator = RegexValidator(  
  pattern: r'^[A-Z][a-z]*$', // Starts with uppercase  
  errorText: "Must start with a capital letter",  
);  
print(validator.validate("flutter")); // Error message  

6. List Validation

final error = RequiredListValidator().validate([]);  
print(error); // "List cannot be empty"  

7. Date Validation

final error = RequiredDateValidator().validate(null);  
print(error); // "A date is required"  

📜 License

MIT – See LICENSE for details.

🔗 Links

• VALIDATOR USAGE