Getting Started

Minimal Setup

Installation:
```
composer require sabre/xml
```
Ensure your composer.json targets PHP 8.2+ (for v4.x) or PHP 7.4+ (for v3.x).

First Use Case: Parse a simple XML string into an associative array:

use Sabre\Xml\Reader;

$reader = new Reader();
$reader->parse('<root><user><name>John</name><email>john@example.com</email></user></root>');
$data = $reader->getParsedData();
// Output: ['user' => ['name' => 'John', 'email' => 'john@example.com']]

Where to Look First:
- Reading XML for parsing logic.
- Writing XML for generating XML.
- Service Class for combined read/write operations (e.g., transforming arrays to XML and back).

Implementation Patterns

Core Workflows

1. Parsing XML with Custom Logic

Use the Reader class with deserializers for complex data:

$reader = new Reader();
$reader->parse('<order><items><item id="101">Laptop</item></items></order>');

// Register a custom deserializer for 'item' elements
$reader->addDeserializer('item', function ($element) {
    return [
        'id' => $element['@id'],
        'name' => $element['#text']
    ];
});

$orders = $reader->getParsedData();
// Output: ['order' => ['items' => [['id' => '101', 'name' => 'Laptop']]]]

2. Generating XML from Arrays

Leverage the Writer for structured XML output:

use Sabre\Xml\Writer;

$writer = new Writer();
$writer->write('<users>', [
    'user' => [
        ['name' => 'Alice', 'role' => 'admin'],
        ['name' => 'Bob', 'role' => 'user']
    ]
]);
echo $writer->getXmlString();
// Output: <users><user><name>Alice</name><role>admin</role></user>...</users>

3. Service Class for Round-Trips

Use Service to parse and rewrite XML in one step:

use Sabre\Xml\Service;

$service = new Service();
$service->parse('<config><database>mysql</database></config>');
$data = $service->getParsedData(); // Parse
$service->write('<new_config>', $data); // Rewrite

4. Laravel Integration

Wrap the library in a service provider or facade for consistency:

// app/Providers/SabreXmlServiceProvider.php
namespace App\Providers;
use Sabre\Xml\Reader;
use Illuminate\Support\ServiceProvider;

class SabreXmlServiceProvider extends ServiceProvider {
    public function register() {
        $this->app->singleton('sabre.xml.reader', function () {
            return new Reader();
        });
    }
}

$reader = app('sabre.xml.reader');

5. Handling Namespaces

Use parseClarkNotation for namespace-aware parsing:

$reader = new Reader();
$reader->parse('<ns:root xmlns:ns="http://example.com/ns"><ns:item>Value</ns:item></ns:root>');
$data = $reader->parseClarkNotation('ns:item');

6. Error Handling

Catch Sabre\Xml\Exception for malformed XML:

try {
    $reader->parse('<invalid>xml</invalid>');
} catch (\Sabre\Xml\Exception $e) {
    report($e); // Log via Laravel's error handler
}

Integration Tips

Validation: Combine with Laravel’s Validator for schema validation:

use Illuminate\Support\Facades\Validator;

$data = $reader->getParsedData();
$validator = Validator::make($data, [
    'user.name' => 'required|string',
    'user.email' => 'required|email'
]);

Caching: Cache parsed XML responses (e.g., for SOAP APIs):

$cacheKey = 'soap_response_' . md5($request->getContent());
$data = Cache::remember($cacheKey, now()->addHours(1), function () use ($reader) {
    return $reader->parse($request->getContent())->getParsedData();
});

Testing: Use Laravel’s XmlReader mocks in PHPUnit:

$mockReader = $this->createMock(\Sabre\Xml\Reader::class);
$mockReader->method('getParsedData')->willReturn(['test' => 'data']);
$this->app->instance('sabre.xml.reader', $mockReader);

SOAP Integration: Pair with php-soap for SOAP services:

$client = new \SoapClient($wsdl);
$response = $client->__doRequest($xml, $location, $action, $version);
$reader = new Reader();
$reader->parse($response);

Gotchas and Tips

Pitfalls

Closed Resource Handling:
- Issue: Passing a closed stream/resource to parse() or expect() throws an exception.
- Fix: Reopen the resource or use fopen()/tmpfile():
```
$resource = fopen('php://temp', 'r+');
fwrite($resource, $xmlString);
rewind($resource);
$reader->parse($resource);
```
Namespace Quirks:
- Issue: Elements from foreign namespaces may not appear in getParsedData() by default.
- Fix: Use parseClarkNotation() or enable namespace handling:
```
$reader->setNamespaceHandling(true);
```
Empty XML Elements:
- Issue: Empty elements (e.g., <tag></tag>) may cause infinite loops in older versions.
- Fix: Upgrade to v2.2.1+ or explicitly handle empty nodes:
```
$reader->addDeserializer('empty_tag', function () {
    return null; // Explicitly return null for empty tags
});
```

Type Declarations (v3+):

Issue: Extending classes in v3 requires type hints for parameters/returns.

Fix: Update your code to match Sabre’s type signatures:

class CustomReader extends \Sabre\Xml\Reader {
    public function customParse(string $xml): array {
        return $this->parse($xml)->getParsedData();
    }
}

PHP 8.2+ Compatibility:
- Issue: Some methods may throw TypeError if not using v4.x.
- Fix: Pin to sabre/xml:^4.0 in composer.json for PHP 8.2+:
```
"require": {
    "sabre/xml": "^4.0"
}
```

Debugging Tips

Enable Verbose Errors: Configure libxml for detailed error messages:

libxml_use_internal_errors(true);
$reader->parse($xml);
$errors = libxml_get_errors();
foreach ($errors as $error) {
    report("XML Error: {$error->message}");
}
libxml_clear_errors();

Inspect Parsed Structure: Use debug() to dump the parsed data:

$data = $reader->getParsedData();
\Illuminate\Support\Facades\Log::debug('Parsed XML:', $data);

Check for Malformed XML: Validate XML before parsing:

if (!\Sabre\Xml\Reader::isValidXml($xmlString)) {
    throw new \InvalidArgumentException('Invalid XML provided.');
}

Extension Points

Custom Deserializers: Extend functionality by adding deserializers for domain-specific XML:

$reader->addDeserializer('invoice', function ($element) {
    return [
        'amount' => (float) $element['@amount'],
        'currency' => $element['@currency'],
        'items' => array_map(function ($item) {
            return ['product' => $item['#text'],

Xml Laravel Package