JSON, XML and Serialization

<?php

declare(strict_types=1);

$payload = '{"isbn": "978-0-00-000001-1", "copies": 3, "id": 12345678901234567890}';
$data = json_decode($payload, true, flags: JSON_THROW_ON_ERROR | JSON_BIGINT_AS_STRING);
var_dump($data['copies'], $data['id']);         // int(3) string(20) "12345678901234567890"

try {
    json_decode('{"isbn": "978-0",}', true, flags: JSON_THROW_ON_ERROR);
} catch (JsonException $e) {
    echo $e->getMessage(), "\n";                // Syntax error
}

var_dump(json_validate('{"isbn": "978-0"}'), json_validate('{isbn: 1}'));   // bool(true) bool(false) -- 8.3

try {
    json_encode("broken \xff byte", JSON_THROW_ON_ERROR);
} catch (JsonException $e) {
    echo $e->getMessage(), "\n";                // Malformed UTF-8 characters, possibly incorrectly encoded
}

<?php

declare(strict_types=1);

final readonly class Loan implements JsonSerializable
{
    public function __construct(
        private string $isbn,
        private DateTimeImmutable $due,
        private int $renewals = 0,
    ) {}

    public function jsonSerialize(): array
    {
        return [
            'isbn' => $this->isbn,
            'due_at' => $this->due->format(DateTimeInterface::ATOM),
            'renewable' => $this->renewals < 2,
        ];
    }
}

echo json_encode([new Loan('978-0-00-000001-1', new DateTimeImmutable('2026-10-26T00:00:00Z'))], JSON_THROW_ON_ERROR), "\n";
// [{"isbn":"978-0-00-000001-1","due_at":"2026-10-26T00:00:00+00:00","renewable":true}]

<?php

declare(strict_types=1);

$xml = <<<'XML'
<?xml version="1.0" encoding="UTF-8"?>
<catalogue>
  <book isbn="978-0-00-000001-1"><title>Kindred</title><year>1979</year></book>
  <book isbn="978-0-00-000003-5"><title>Solaris</title><year>1961</year></book>
</catalogue>
XML;

$catalogue = simplexml_load_string($xml);
foreach ($catalogue->book as $book) {
    printf("%s %s (%d)\n", $book['isbn'], $book->title, (int) $book->year);   // attributes by [ ], elements by ->
}

$old = $catalogue->xpath('//book[year < 1970]/title');
echo 'before 1970: ', (string) $old[0], "\n";            // before 1970: Solaris

// Parse errors: collect them instead of warnings
libxml_use_internal_errors(true);
var_dump(simplexml_load_string('<catalogue><book>'));     // bool(false)
echo count(libxml_get_errors()) > 0 ? "errors collected\n" : '';
libxml_clear_errors();

<?php

declare(strict_types=1);

$html = <<<'HTML'
<!doctype html>
<main>
  <article class="review" data-stars="5"><h2>Kindred</h2><p>Gripping &amp; humane.</p></article>
  <article class="review" data-stars="3"><h2>Solaris</h2><p>Strange.</p></article>
</main>
HTML;

$doc = Dom\HTMLDocument::createFromString($html);

foreach ($doc->querySelectorAll('article.review') as $review) {
    printf("%s: %d stars\n", $review->querySelector('h2')->textContent, (int) $review->getAttribute('data-stars'));
}

echo $doc->querySelector('article p')->outerHTML, "\n";      // <p>Gripping &amp; humane.</p> (outerHTML: 8.5)

$xml = Dom\XMLDocument::createFromString('<catalogue><book isbn="978-0-00-000001-1"/></catalogue>');
echo $xml->querySelector('book')->getAttribute('isbn'), "\n";

Kindred: 5 stars
Solaris: 3 stars
<p>Gripping &amp; humane.</p>
978-0-00-000001-1

<?php

declare(strict_types=1);

$writer = new XMLWriter();
$writer->openMemory();                                  // or openUri('catalogue.xml')
$writer->setIndent(true);
$writer->startDocument('1.0', 'UTF-8');
$writer->startElement('catalogue');
foreach (['978-0-00-000001-1' => 'Kindred & Dawn', '978-0-00-000003-5' => 'Solaris'] as $isbn => $title) {
    $writer->startElement('book');
    $writer->writeAttribute('isbn', $isbn);
    $writer->writeElement('title', $title);             // escaping is automatic
    $writer->endElement();
}
$writer->endElement();
$xml = $writer->outputMemory();
echo $xml;

$reader = XMLReader::fromString($xml);                  // 8.4 factory; XMLReader::fromUri() for files
$titles = [];
while ($reader->read()) {
    if ($reader->nodeType === XMLReader::ELEMENT && $reader->name === 'title') {
        $titles[] = $reader->readString();
    }
}
echo implode(' | ', $titles), "\n";                     // Kindred & Dawn | Solaris

<?php

declare(strict_types=1);

$xml = new DOMDocument();
$xml->loadXML('<catalogue><book><title>Kindred</title></book><book><title>Solaris</title></book></catalogue>');

$xsl = new DOMDocument();
$xsl->loadXML(<<<'XSL'
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="text"/>
  <xsl:template match="/">
    <xsl:for-each select="catalogue/book"><xsl:value-of select="title"/>;</xsl:for-each>
  </xsl:template>
</xsl:stylesheet>
XSL);

$processor = new XSLTProcessor();
$processor->importStylesheet($xsl);
echo $processor->transformToXml($xml), "\n";     // Kindred;Solaris;