SimpleXML maps elements to object properties and attributes to array keys, which suits reading regular feeds. DOM is the full W3C API; PHP 8.4 added Dom\XMLDocument, a standards-compliant DOM with CSS selectors, alongside the classic DOMDocument. XMLReader and XMLWriter stream large files:
<?php
// SimpleXML: elements as properties, attributes as array keys
$catalog = simplexml_load_file('booknest-catalog.xml');
foreach ($catalog->book as $book) {
if ((float) $book->supply->price >= 20) {
printf("%s %-26s %6.2f\n", $book['id'], $book->title, (float) $book->supply->price);
}
}
// PHP 8.4+ Dom\XMLDocument: standards-based DOM with CSS selectors
$doc = Dom\XMLDocument::createFromFile('booknest-catalog.xml');
$b3 = $doc->querySelector('book[id="b3"]');
$b3->querySelector('availability')->textContent = 'in-stock';
echo $doc->saveXml($b3->querySelector('supply')), PHP_EOL;
echo 'PHP ', PHP_VERSION, ', libxml ', LIBXML_DOTTED_VERSION, PHP_EOL;Output
b2 Patterns of the Deep Web 39.50
b3 Salt and Saffron 24.00
b6 Gardens in Glass 21.30
<supply>
<availability>in-stock</availability>
<price currency="USD">24.00</price>
</supply>
PHP 8.5.4, libxml 2.15.2Cast SimpleXML values ((float), (string)) before comparing them.
DOM Reference
Reference for the classes exposed by PHP's DOM extension (php.net/manual/en/book.dom.php 331 ). All node types extend DOMNode.DOMNode
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readonly string $nodeName; string $nodeValue; readonly int $nodeType; readonly DOMNode $parentNode; readonly DOMNodeList $childNodes; readonly DOMNode $firstChild; readonly DOMNode $lastChild; readonly DOMNode $previousSibling; readonly DOMNode $nextSibling; readonly DOMNamedNodeMap $attributes; readonly DOMDocument $ownerDocument; readonly string $namespaceURI; string $prefix; readonly string $localName; readonly string $baseURI; readonly string $textContent; |
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DOMNode appendChild 331 (DOMNode $newnode) string C14N 331 ([bool $exclusive [, bool $with_comments [, array $xpath [, array $ns_prefixes]]]]) int C14NFile 331 (string $uri [, bool $exclusive [, bool $with_comments [, array $xpath [, array $ns_prefixes]]]]) DOMNode cloneNode 331 ([bool $deep]) int getLineNo 331 (void) string getNodePath 331 (void) bool hasAttributes 331 (void) bool hasChildNodes 331 (void) DOMNode insertBefore 331 (DOMNode $newnode [, DOMNode $refnode]) bool isDefaultNamespace 331 (string $namespaceURI) bool isSameNode 331 (DOMNode $node) bool isSupported 331 (string $feature, string $version) string lookupNamespaceURI 331 (string $prefix) string lookupPrefix 331 (string $namespaceURI) void normalize 331 (void) DOMNode removeChild 331 (DOMNode $oldnode) DOMNode replaceChild 331 (DOMNode $newnode, DOMNode $oldnode) |
DOMDocument extends DOMNode
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readonly string $actualEncoding; readonly DOMConfiguration $config; readonly DOMDocumentType $doctype; readonly DOMElement $documentElement; string $documentURI; string $encoding; bool $formatOutput; readonly DOMImplementation $implementation; bool $preserveWhiteSpace = true; bool $recover; bool $resolveExternals; bool $standalone; bool $strictErrorChecking = true; bool $substituteEntities; bool $validateOnParse = false; string $version; readonly string $xmlEncoding; bool $xmlStandalone; string $xmlVersion; |
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__construct 331 ([string $version [, string $encoding]]) DOMAttr createAttribute 331 (string $name) DOMAttr createAttributeNS 331 (string $namespaceURI, string $qualifiedName) DOMCDATASection createCDATASection 331 (string $data) DOMComment createComment 331 (string $data) DOMDocumentFragment createDocumentFragment 331 (void) DOMElement createElement 331 (string $name [, string $value]) DOMElement createElementNS 331 (string $namespaceURI, string $qualifiedName [, string $value]) DOMEntityReference createEntityReference 331 (string $name) DOMProcessingInstruction createProcessingInstruction 331 (string $target [, string $data]) DOMText createTextNode 331 (string $content) DOMElement getElementById 331 (string $elementId) DOMNodeList getElementsByTagName 331 (string $name) DOMNodeList getElementsByTagNameNS 331 (string $namespaceURI, string $localName) DOMNode importNode 331 (DOMNode $importedNode [, bool $deep]) mixed load 331 (string $filename [, int $options = 0]) bool loadHTML 331 (string $source [, int $options = 0]) bool loadHTMLFile 331 (string $filename [, int $options = 0]) mixed loadXML 331 (string $source [, int $options = 0]) void normalizeDocument 331 (void) bool registerNodeClass 331 (string $baseclass, string $extendedclass) bool relaxNGValidate 331 (string $filename) bool relaxNGValidateSource 331 (string $source) int save 331 (string $filename [, int $options]) string saveHTML 331 ([DOMNode $node = NULL]) int saveHTMLFile 331 (string $filename) string saveXML 331 ([DOMNode $node [, int $options]]) bool schemaValidate 331 (string $filename [, int $flags]) bool schemaValidateSource 331 (string $source [, int $flags]) bool validate 331 (void) int xinclude 331 ([int $options]) |
For the save*() functions, only LIBXML_NOEMPTYTAG is a supported $options value. For the load*() functions and xinclude(), $options accepts any combination of the libxml constants 331 : LIBXML_COMPACT, LIBXML_DTDATTR, LIBXML_DTDLOAD, LIBXML_DTDVALID, LIBXML_HTML_NOIMPLIED, LIBXML_HTML_NODEFDTD, LIBXML_NOBLANKS, LIBXML_NOCDATA, LIBXML_NOEMPTYTAG, LIBXML_NOENT, LIBXML_NOERROR, LIBXML_NONET, LIBXML_NOWARNING, LIBXML_NOXMLDECL, LIBXML_NSCLEAN, LIBXML_PARSEHUGE, LIBXML_PEDANTIC, LIBXML_XINCLUDE, LIBXML_ERR_ERROR, LIBXML_ERR_FATAL, LIBXML_ERR_NONE, LIBXML_ERR_WARNING, LIBXML_VERSION, LIBXML_DOTTED_VERSION, LIBXML_SCHEMA_CREATE. The methods loadXML(), loadHTML(), saveXML(), saveHTML(), relaxNGValidateSource(), and schemaValidateSource() operate on an in-memory string rather than a file.
DOMElement extends DOMNode
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readonly bool $schemaTypeInfo; readonly string $tagName; |
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__construct 331 (string $name [, string $value [, string $namespaceURI]]) string getAttribute 331 (string $name) DOMAttr getAttributeNode 331 (string $name) DOMAttr getAttributeNodeNS 331 (string $namespaceURI, string $localName) string getAttributeNS 331 (string $namespaceURI, string $localName) DOMNodeList getElementsByTagName 331 (string $name) DOMNodeList getElementsByTagNameNS 331 (string $namespaceURI, string $localName) bool hasAttribute 331 (string $name) bool hasAttributeNS 331 (string $namespaceURI, string $localName) bool removeAttribute 331 (string $name) bool removeAttributeNode 331 (DOMAttr $oldnode) bool removeAttributeNS 331 (string $namespaceURI, string $localName) DOMAttr setAttribute 331 (string $name, string $value) DOMAttr setAttributeNode 331 (DOMAttr $attr) DOMAttr setAttributeNodeNS 331 (DOMAttr $attr) void setAttributeNS 331 (string $namespaceURI, string $qualifiedName, string $value) void setIdAttribute 331 (string $name, bool $isId) void setIdAttributeNode 331 (DOMAttr $attr, bool $isId) void setIdAttributeNS 331 (string $namespaceURI, string $localName, bool $isId) |
DOMAttr extends DOMNode
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readonly string $name; readonly DOMElement $ownerElement; readonly bool $schemaTypeInfo; readonly bool $specified; string $value; |
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__construct 331 (string $name [, string $value]) bool isId 331 (void) |
DOMDocumentFragment extends DOMNode
| bool appendXML 331 (string $data) |
DOMDocumentType extends DOMNode
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readonly string $Id; // publicId readonly string $systemId; readonly string $name; readonly DOMNamedNodeMap $entities; readonly DOMNamedNodeMap $notations; readonly string $internalSubset; |
DOMNotation extends DOMNode
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readonly string $Id; // publicId readonly string $systemId; |
DOMEntity extends DOMNode
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readonly string $Id; // publicId readonly string $systemId; readonly string $notationName; string $actualEncoding; readonly string $encoding; readonly string $version; |
DOMEntityReference extends DOMNode
| __construct 331 (string $name) |
DOMProcessingInstruction extends DOMNode
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readonly string $target; string $data; |
| __construct 331 (string $name [, string $value]) |
DOMCharacterData extends DOMNode
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string $data; readonly int $length; |
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void appendData 331 (string $data) void deleteData 331 (int $offset, int $count) void insertData 331 (int $offset, string $data) void replaceData 331 (int $offset, int $count, string $data) string substringData 331 (int $offset, int $count) |
DOMComment extends DOMCharacterData
| __construct 331 ([string $value]) |
DOMText extends DOMCharacterData
| readonly string $wholeText; |
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__construct 331 ([string $value]) bool isWhitespaceInElementContent 331 (void) DOMText splitText 331 (int $offset) |
DOMCdataSection extends DOMText
| __construct 331 (string $value) |
DOMNamedNodeMap implements Traversable
| readonly int $length; |
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DOMNode getNamedItem 331 (string $name) DOMNode getNamedItemNS 331 (string $namespaceURI, string $localName) DOMNode item 331 (int $index) |
DOMNodeList implements Traversable
| readonly int $length; |
| DOMNode item 331 (int $index) |
DOMException extends Exception
| readonly int $code; |
DOMImplementation
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__construct 331 (void) DOMDocument createDocument 331 ([string $namespaceURI = NULL [, string $qualifiedName = NULL [, DOMDocumentType $doctype = NULL]]]) DOMDocumentType createDocumentType 331 ([string $qualifiedName = NULL [, string $Id = NULL [, string $systemId = NULL]]]) bool hasFeature 331 (string $feature, string $version) |
Reading
To read an XML document, load it into a DOMDocument with load(), then navigate it with methods such as getElementsByTagName().If the document contains XInclude directives, call $doc->xinclude() after loading to resolve them and merge in the included content. The example below loads people.xml, which pulls in the two <person> elements of people2.xml via <xi:include>, then iterates over all four <person> elements, printing each child element's text and the id attribute.
merged-02-01-ch08-people.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!-- people.xml -->
<people xmlns:xi="http://www.w3.org/2003/XInclude">
<xi:include href="people2.xml" parse="xml">
<xi:fallback>
<error>xinclude: people2.xml not found</error>
</xi:fallback>
</xi:include>
<person id="p3">
<name>Eric Lee</name>
<gender>m</gender>
<age>35</age>
</person>
<person id="p4">
<name>Serena</name>
<gender>f</gender>
<age>25</age>
</person>
</people>
merged-02-02-ch08-people2.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!-- people2.xml -->
<people>
<person id="p1">
<name>Alexander Mike</name>
<gender>m</gender>
<age>40</age>
</person>
<person id="p2">
<name>Celeste</name>
<gender>f</gender>
<age>15</age>
</person>
</people>
<!DOCTYPE html>
<html><head></head><body><?php
$doc = new DOMDocument();
$doc->load('people.xml');
$doc->xinclude();
$persons = $doc->getElementsByTagName('person');
foreach ($persons as $person){
$v = $person->getElementsByTagName('*');
for ($i=0; $i<$v->length; $i++){
echo $v->item($i)->nodeValue.",";
}
echo $person->attributes->getNamedItem('id')->value;
echo "<br/>";
}
?></body></html>
Output
Alexander Mike,m,40,p1 Celeste,f,15,p2 Eric Lee,m,35,p3 Serena,f,25,p4
Writing
Build a new XML document with DOMDocument, then write it to disk with save(). The example below constructs book.xml: a document with a top-level comment, a root <book> element, and a nested <part> element whose title attribute is registered as an ID attribute via setIdAttribute(). One <chapter> child is appended to <part> for each entry in a PHP array.<!DOCTYPE html>
<html><head></head><body><?php
$doc = new DOMDocument("1.0","UTF-8");
$comment=$doc->createComment("This is 'book.xml'.");
$doc->appendChild($comment);
$book=$doc->createElement("book");
$doc->appendChild($book);
$part1 = new DOMElement("part");
$book->appendChild($part1);
$part1->setAttribute("title","Core");
$part1->setIdAttribute("title",true);
$chapters = ["HTML","CSS","JavaScript","PHP","SQL","XML"];
foreach ($chapters as $chapter){
$c = new DOMElement("chapter",$chapter);
$part1->appendChild($c);
}
$doc->save("book.xml");
?></body></html>
