clean_string_validator

A lightweight, dependency-free Dart package that adds fluent String validation through extension methods — no utility classes, no static method calls, just clean, readable code:

"john@gmail.com".isValidEmail;       // true
"Password@123".isStrongPassword;     // true
"https://flutter.dev".isValidUrl;    // true
"+923001234567".isValidPhone;        // true
"123".isNumeric;                     // true

Features

  • ✅ Zero dependencies — pure Dart, works in Flutter, server, and CLI apps
  • ✅ Fluent, discoverable API via extension methods
  • ✅ Centralized, non-duplicated regex patterns
  • ✅ Clear separation between validators and extensions
  • ✅ Extensively unit tested
  • ✅ Fully documented with dartdoc comments
  • ✅ Zero analyzer warnings, lints-compliant
  • ✅ Easy to extend with new validators

Installation

Add this to your pubspec.yaml:

dependencies:
  clean_string_validator: ^1.0.0

Then run:

dart pub get

Or, for Flutter projects:

flutter pub get

Usage

Import the single public entry point:

import 'package:clean_string_validator/clean_string_validator.dart';

That's it — every extension method below becomes available on any String.

Supported Validators

Email

Method Description
.isValidEmail Checks for a syntactically valid email 
"john@gmail.com".isValidEmail; // true

Password

Method Description
.isStrongPassword At least 8 chars, upper, lower, digit, and special character 
"Password@123".isStrongPassword; // true

Phone

Method Description
.isValidPhone Validates Pakistani and generic international numbers 
"+923001234567".isValidPhone; // true
"03001234567".isValidPhone;   // true

URL

Method Description
.isValidUrl Validates HTTP/HTTPS URLs 
"https://flutter.dev".isValidUrl; // true

Username

Method Description
.isValidUsername 3-20 chars: letters, numbers, underscores only 
"john_doe123".isValidUsername; // true

Numbers

Method Description
.isNumeric Parses as any number
.isInteger Parses as an integer
.isDouble Parses as a double
.isPositiveNumber Numeric value greater than zero
.isNegativeNumber Numeric value less than zero 
"123".isNumeric;         // true
"42".isInteger;          // true
"42.5".isDouble;         // true
"10".isPositiveNumber;   // true
"-10".isNegativeNumber;  // true

Date

Method Description
.isValidDate Validates real YYYY-MM-DD calendar dates 
"2024-05-10".isValidDate; // true
"2024-02-30".isValidDate; // false

JSON

Method Description
.isJson Checks for syntactically valid JSON 
'{"name":"John"}'.isJson; // true

UUID

Method Description
.isUUID Validates UUID versions 1-5 
"123e4567-e89b-12d3-a456-426614174000".isUUID; // true

IPv4 / IPv6 / MAC Address

Method Description
.isIPv4 Validates IPv4 addresses
.isIPv6 Validates IPv6 addresses
.isMacAddress Validates MAC addresses 
"192.168.0.1".isIPv4;             // true
"::1".isIPv6;                     // true
"00:1B:44:11:3A:B7".isMacAddress; // true

Hex Color

Method Description
.isHexColor Validates 3 or 6 digit hex colors (# optional) 
"#fff".isHexColor;    // true
"#ffffff".isHexColor; // true

Credit Card

Method Description
.isValidCreditCard Validates length and Luhn checksum 
"4539578763621486".isValidCreditCard; // true

Text Helpers

Method Description
.isBlank Empty or whitespace only
.isNotBlank Has non-whitespace content
.hasText Alias for .isNotBlank
.isWhitespace Non-empty and whitespace only
.containsUppercase Has at least one uppercase letter
.containsLowercase Has at least one lowercase letter
.containsNumber Has at least one digit
.containsSpecialCharacter Has at least one special character
.containsOnlyLetters All characters are letters
.containsOnlyDigits All characters are digits
.isAlphabet Alias for .containsOnlyLetters
.isAlphaNumeric All characters are letters or digits
.hasMinLength(int) Length ≥ given value
.hasMaxLength(int) Length ≤ given value
.hasExactLength(int) Length equals given value
.isUpperCase Entirely uppercase
.isLowerCase Entirely lowercase
.isTitleCase Every word capitalized (Hello World)

Folder Structure

clean_string_validator/
├── lib/
│   ├── clean_string_validator.dart   # Public API barrel file
│   └── src/
│       ├── extensions/               # Fluent extension methods
│       ├── validators/               # Pure validation logic
│       ├── regex/                    # Centralized regex patterns
│       └── utils/                    # Shared helpers (Luhn, constants, etc.)
├── example/
│   └── main.dart
├── test/
│   └── ...                           # One test file per validator
├── CHANGELOG.md
├── LICENSE
└── pubspec.yaml

Design Principles

  • No duplicated regex — every pattern lives in regex_patterns.dart.
  • Validators know nothing about extensions — they're plain, testable static methods.
  • Extensions only expose clean getters/methods — no business logic.
  • This separation makes it trivial to add new validators (email masking, OTP, PIN, slugs, country-specific rules, etc.) without touching existing files.

Contributing

Contributions are welcome! To add a new validator:

  1. Add any new regex to lib/src/regex/regex_patterns.dart.
  2. Create a validator in lib/src/validators/ with static methods.
  3. Create an extension in lib/src/extensions/ that calls the validator.
  4. Export the new extension from lib/clean_string_validator.dart.
  5. Add tests covering valid, invalid, empty, and boundary cases.

Please run dart analyze and dart test before submitting a pull request.

License

This package is released under the MIT License.

Libraries

clean_string_validator
clean_string_validator