Lemonade Postcode

A lightweight PHP library for validating and formatting international postal codes (ZIP/PSC).
Provides country-specific formatters, unified exception handling, and clear error codes for integration in forms, APIs, and e-commerce applications.

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✨ Features

• ✅ Validation and normalization of postal codes for multiple countries
• ✅ Country-specific formatters (CZ, SK, DE, GB, FR, IT, …)
• ✅ Unified API via PostcodeFormatter
• ✅ Strict typing (PHP 8.1+)
• ✅ Consistent error handling with PostcodeException and PostcodeErrorCode enum
• ✅ Ready for localization (messageKey() for translation keys)
• ✅ PSR-4 autoloading
• ✅ PHPUnit test coverage
• ✅ PHPStan Level 10 + Strict Rules
• ✅ Verified with 100% PHPUnit coverage
• ✅ Includes support for all 249 ISO 3166-1 alpha-2 country codes

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🚀 Installation

  composer require lemonade/component_postcode

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🔧 Usage

use Lemonade\Postcode\PostcodeFormatter;
use Lemonade\Postcode\CountryCode;
use Lemonade\Postcode\Exception\PostcodeException;
use Lemonade\Postcode\FormatterRegistry;

// initialize with default formatters
$registry  = new FormatterRegistry();          // IMMUTABLE REGISTRY
$formatter = new PostcodeFormatter($registry); // READONLY REFERENCE

try {
    $postcode = $formatter->format(CountryCode::CZ, '12000');
    // "120 00"
} catch (PostcodeException $e) {
    echo $e->getValue() . ' is invalid: ' . $e->getMessage();
}

➕ Custom Formatters

You can easily extend the library with your own country-specific formatters.
Simply implement CountryPostcodeFormatter and register it via FormatterRegistry.

Example with an anonymous class:

use Lemonade\Postcode\CountryCode;
use Lemonade\Postcode\CountryPostcodeFormatter;
use Lemonade\Postcode\Exception\InvalidPostcodeException;
use Lemonade\Postcode\FormatterRegistry;
use Lemonade\Postcode\PostcodeFormatter;

$registry = new FormatterRegistry();

// Add custom formatter for Antarctica (AQ)
$registry = $registry->register(CountryCode::AQ, new class implements CountryPostcodeFormatter {
    public function format(string $postcode): string
    {
        if (preg_match('/^[0-9]{4}$/', $postcode) !== 1) {
            throw new InvalidPostcodeException($postcode);
        }
        return strtoupper($postcode);
    }
});

$formatter = new PostcodeFormatter($registry);

try {
    echo $formatter->format(CountryCode::AQ, '1231');
    // outputs "1231"
} catch (InvalidPostcodeException $e) {
    echo $e->getValue() . ' is invalid: ' . $e->getMessage();
}

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📦 Country Formatters

Each country has its own Formatter class under Lemonade\Postcode\Formatter.
Examples:

• CZ_Formatter – 12000 → 120 00
• SK_Formatter – 81101 → 811 01
• PL_Formatter – 01001 → 01-001
• GB_Formatter – SW1A1AA → SW1A 1AA
• LT_Formatter – supports both 12345 and LT12345

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⚠️ Exceptions

All errors are reported using dedicated exception classes.
This makes it easy to distinguish between invalid input and unsupported countries.

• InvalidPostcodeException
  Thrown when the postcode does not match the expected format
  or contains an unsupported value.
  Example: "ABCDE" for CZ.

• UnknownCountryException
  Thrown when trying to format a postcode for an unsupported
  or unrecognized ISO 3166-1 alpha-2 country code.
  Example: "XX".

• UnsupportedCountryException
  Thrown when the country code is valid, but no formatter is registered for it.

  Example: "AQ" (valid ISO code, but not implemented in FormatterMapper)..

All exceptions implement the PostcodeException interface, which provides:

• getValue() → returns the original input (postcode or country)
• getCode() → stable numeric error code (PostcodeErrorCode)
• getMessage() → translation key for localization

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📖 Changelog

All notable changes are documented in the CHANGELOG.md.

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🧪 Development & Testing

This package is fully covered by PHPUnit tests and verified with PHPStan Level 10.

Run PHPUnit tests:

  composer install
  vendor/bin/phpunit
  vendor/bin/phpunit -c vendor/lemonade/component_postcode/phpunit.xml --bootstrap vendor/autoload.php

Run static analysis (PHPStan Level 10 + Strict Rules):

  vendor/bin/phpstan analyse vendor/lemonade/component_postcode/src \
    --configuration=vendor/lemonade/component_postcode/phpstan.neon.dist \
    --memory-limit=1G