PHP : XML Create-Add-Edit-Modify using DOM, SimpleXML, XPath
Written on September 4, 2010
Estimated reading time :
21 mins
Note
This is an old popular post from my personal blog. I moved it here so as to get all my technical content together.
Over the last few working days, I spent a quite a bit of time playing around with XML. While searching through the net, I found few comprehensive PHP XML guides. There never was a ‘1 stop all operations’ guide for learning XML.
As such I decided to club together examples of all kinds of operations I ever did on XML in a single post. I hope it benefits others out there who wish to learn more about XML manipulation.
Note : Since the post got quite large, I decided to only use the Tree Map style parsers – DOM & Simple XML.
Operations Performed
- Create XML OR Array to XML Conversion OR CDATA Element
- Edit XML – Edit/Modify Element Data (accessed serially)
- Edit XML – Edit specific Elements (accessed conditionally)
- Edit XML – Element Addition (to queue end)
- Edit XML – Element Addition (to queue start)
- Edit XML – Element Addition (before a specific node)
- Delete Elements (accessed serially)
- Delete Elements (accessed conditionally)
- Rearrange / Reorder Elements
- Display Required data in XML Form itself OR Remove all children nodes save one OR Copy/Clone Node Eg OR Compare/Search non numeric data (like date or time) to get result.
Following content from library.xml will be used in all operations :
<?xml version="1.0"?>
<library>
<book isbn="1001" pubdate="1943-01-01">
<title><![CDATA[The Fountainhead]]></title>
<author>Ayn Rand</author>
<price>300</price>
</book>
<book isbn="1002" pubdate="1954-01-01">
<title><![CDATA[The Lord of the Rings]]></title>
<author>J.R.R.Tolkein</author>
<price>500</price>
</book>
<book isbn="1003" pubdate="1982-01-01">
<title><![CDATA[The Dark Tower]]></title>
<author>Stephen King</author>
<price>200</price>
</book>
</library>
1. Create XML OR Array to XML Conversion OR CDATA Element
SimpleXML :
// Cant create CDATA element for title in SimpleXML.
function fnSimpleXMLCreate() {
$arr = array(array('isbn'=>'1001', 'pubdate'=>'1943-01-01', 'title'=>'The Fountainhead',
'author'=>'Ayn Rand', 'price'=>'300'),
array('isbn'=>'1002', 'pubdate'=>'1954-01-01',
'title'=>'The Lord of the Rings', 'author'=>'J.R.R.Tolkein',
'price'=>'500'),
array('isbn'=>'1003', 'pubdate'=>'1982-01-01', 'title'=>'The Dark Tower',
'author'=>'Stephen King', 'price'=>'200'));
$library = new SimpleXMLElement('<library />');
for($i = 0; $i < 3; $i++) {
$book = $library->addChild('book');
$book->addAttribute('isbn', $arr[$i]['isbn']);
$book->addAttribute('pubdate', $arr[$i]['pubdate']);
$book->addChild('title', $arr[$i]['title']); //cant create CDATA in SimpleXML.
$book->addChild('author', $arr[$i]['author']);
$book->addChild('price', $arr[$i]['price']);
}
// header("Content-type: text/xml");
// echo $library->asXML();
$library->asXML('library.xml');
}
DOM :
function fnDomCreate() {
$arr = array(array('isbn'=>'1001', 'pubdate'=>'1943-01-01', 'title'=>'The Fountainhead',
'author'=>'Ayn Rand', 'price'=>'300'),
array('isbn'=>'1002', 'pubdate'=>'1954-01-01',
'title'=>'The Lord of the Rings', 'author'=>'J.R.R.Tolkein',
'price'=>'500'),
array('isbn'=>'1003', 'pubdate'=>'1982-01-01', 'title'=>'The Dark Tower',
'author'=>'Stephen King', 'price'=>'200'));
$dom = new DOMDocument();
$library = $dom->createElement('library');
$dom->appendChild($library);
for($i = 0; $i < 3; $i++) {
$book = $dom->createElement('book');
$book->setAttribute('isbn',$arr[$i]['isbn']);
$book->setAttribute('pubdate',$arr[$i]['pubdate']);
//$prop = $dom->createElement('title', $arr[$i]['title']);
$prop = $dom->createElement('title');
$text = $dom->createCDATASection($arr[$i]['title']);
$prop->appendChild($text);
$book->appendChild($prop);
$prop = $dom->createElement('author', $arr[$i]['author']);
$book->appendChild($prop);
$prop = $dom->createElement('price', $arr[$i]['price']);
$book->appendChild($prop);
$library->appendChild($book);
}
//header("Content-type: text/xml");
$dom->save('library.xml');
}
2. Edit XML – Edit/Modify Element Data (accessed serially)
SimpleXML :
// Edit Last Book Title
function fnSimpleXMLEditElementSeq() {
$library = new SimpleXMLElement('library.xml',null,true);
$num = count($library);
$library->book[$num-1]->title .= ' - The Gunslinger';
// header("Content-type: text/xml");
// echo $library->asXML();
$library->asXML('library_modified.xml');
}
DOM :
// Edit Last Book Title
function fnDOMEditElementSeq() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$cnt = $library->childNodes->length;
$library->childNodes->item($cnt-1)->getElementsByTagName('title')->item(0)->nodeValue .= ' Series';
// 2nd way #$library->getElementsByTagName('book')->item($cnt-1)->getElementsByTagName('title')->item(0)->nodeValue .= ' Series';
// 3rd Way
// $library->childNodes->item($cnt-1)->childNodes->item(0)->nodeValue .= ' Series';
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
3. Edit XML – Edit specific Elements (accessed conditionally)
SimpleXML :
// Edit Title of book with author J.R.R.Tolkein
function fnSimpleXMLEditElementCond() {
$library = new SimpleXMLElement('library.xml',null,true);
$book = $library->xpath('/library/book[author="J.R.R.Tolkein"]');
$book[0]->title .= ' Series';
// header("Content-type: text/xml");
// echo $library->asXML();
$library->asXML('library_modified.xml');
}
DOM :
// Edit Title of book with author J.R.R.Tolkein
function fnDOMEditElementCond() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$xpath = new DOMXPath($dom);
$result = $xpath->query('/library/book[author="J.R.R.Tolkein"]/title');
$result->item(0)->nodeValue .= ' Series';
// This will remove the CDATA property of the element.
// To retain it, delete this element (see delete eg) & recreate it with CDATA (see create xml eg).
// 2nd Way
// $result = $xpath->query('/library/book[author="J.R.R.Tolkein"]');
// $result->item(0)->getElementsByTagName('title')->item(0)->nodeValue .= ' Series';
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
4. Edit XML – Element Addition (to queue end)
SimpleXML :
// Add another Book to the end
function fnSimpleXMLAddElement2End() {
$library = new SimpleXMLElement('library.xml',null,true);
$book = $library->addChild('book');
$book->addAttribute('isbn', '1004');
$book->addAttribute('pubdate', '1960-07-11');
$book->addChild('title', "To Kill a Mockingbird");
$book->addChild('author', "Harper Lee");
$book->addChild('price', "100");
// header("Content-type: text/xml");
// echo $library->asXML();
$library->asXML('library_modified.xml');
}
DOM :
// Add another Book to the end
function fnDOMAddElement2End() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$book = $dom->createElement('book');
$book->setAttribute('isbn', '1000');
$book->setAttribute('pubdate','1960-07-11');
$prop = $dom->createElement('title');
$text = $dom->createTextNode('To Kill a Mockingbird');
$prop->appendChild($text);
$book->appendChild($prop);
$prop = $dom->createElement('author', 'Harper Lee');
$book->appendChild($prop);
$prop = $dom->createElement('price', '100');
$book->appendChild($prop);
$library->appendChild($book);
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
5. Edit XML – Element Addition (to queue start)
SimpleXML :
// Add a Book to List Start
// Insert Before Functionality not present in SimpleXML
// We can integrate DOM with SimpleXML to do it.
function fnSimpleXMLAddElement2Start() {
$libSimple = new SimpleXMLElement('library.xml',null,true);
$libDom = dom_import_simplexml($libSimple);
$dom = new DOMDocument();
//returns a copy of the node to import
$libDom = $dom->importNode($libDom, true);
//associate it with the current document.
$dom->appendChild($libDom);
fnDOMAddElement2Start($dom); //see below DOM function
}
DOM :
function fnDOMAddElement2Start($dom='') {
if (!$dom) {
$dom = new DOMDocument();
$dom->load('library.xml');
}
$library = $dom->documentElement;
#var_dump($library->childNodes->item(0)->parentNode->nodeName);
$book = $dom->createElement('book');
$book->setAttribute('isbn', '1000');
$book->setAttribute('pubdate', '1960-07-11');
$prop = $dom->createElement('title', 'To Kill a Mockingbird');
$book->appendChild($prop);
$prop = $dom->createElement('author', 'Harper Lee');
$book->appendChild($prop);
$prop = $dom->createElement('price', '100');
$book->appendChild($prop);
$library->childNodes->item(0)->parentNode->insertBefore($book, $library->childNodes->item(0));
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
6. Edit XML – Element Addition (before a specific node)
SimpleXML :
// Add a Book Before attribute isbn 1002
// Insert Before Functionality not present in SimpleXML
// We can integrate DOM with SimpleXML to do it.
function fnSimpleXMLAddElementCond() {
$libSimple = new SimpleXMLElement('library.xml', null, true);
$libDom = dom_import_simplexml($libSimple);
$dom = new DOMDocument();
//returns a copy of the node to import
$libDom = $dom->importNode($libDom, true);
//associate it with the current document.
$dom->appendChild($libDom);
fnDOMAddElementCond($dom); //see below DOM eg.
}
DOM :
// Add a Book Before isbn 1002
function fnDOMAddElementCond($dom='')
{
if(!$dom) {
$dom = new DOMDocument();
$dom->load('library.xml');
}
$library = $dom->documentElement;
$book = $dom->createElement('book');
$book->setAttribute('isbn','1000');
$book->setAttribute('pubdate', '1960-07-11');
$prop = $dom->createElement('title', 'To Kill a Mockingbird');
$book->appendChild($prop);
$prop = $dom->createElement('author', 'Harper Lee');
$book->appendChild($prop);
$prop = $dom->createElement('price', '100');
$book->appendChild($prop);
$xpath = new DOMXPath($dom);
$result = $xpath->query('/library/book[@isbn="1002"]');
$library->childNodes->item(0)->parentNode->insertBefore($book,$result->item(0));
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
7. Delete Elements (accessed serially)
SimpleXML :
// Delete 2nd book
function fnSimpleXMLDeleteSeq() {
$library = new SimpleXMLElement('library.xml', null, true);
//$library->book[1] = null; // this only empties content
unset($library->book[1]);
// header("Content-type: text/xml");
// echo $library->asXML();
$library->asXML('library_modified.xml');
}
DOM :
// Delete 2nd Book
function fnDOMDeleteSeq() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$library->childNodes->item(0)->parentNode->removeChild($library->childNodes->item(1));
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
8. Delete Elements (accessed conditionally)
SimpleXML :
// Delete a book with 200<price<500
// Not possible to delete node found via XPath in SimpleXML. See below.
function fnSimpleXMLDeleteCond() {
$library = new SimpleXMLElement('library.xml',null,true);
$book = $library->xpath('/library/book[price>"200" and price<"500"]');
// Problem here....not able to delete parent node using unset($book[0]);
// unset of parent node only works when accessing serially. eg : unset($library->book[0]);
// header("Content-type: text/xml");
// echo $library->asXML();
//$library->asXML('library_modified.xml');
}
DOM :
// Delete the book with 200<price<500
function fnDOMDeleteCond() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$xpath = new DOMXPath($dom);
$result = $xpath->query('/library/book[price>"200" and price<"500"]');
$result->item(0)->parentNode->removeChild($result->item(0));
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
9. Rearrange / Reorder Elements
SimpleXML :
// Exchange Position of 2nd book with 3rd : fnSimpleXMLRearrange(2,3);
// Due to absence of an inbuilt function (DOM has it), we have to make our own function in SimpleXML.
//Better to use DOM.
function fnSimpleXMLRearrange($num1,$num2) {
$libSimple= new SimpleXMLElement('library.xml',null,true);
//$library->book[3] = $library->book[0]; // this doesnt work
$libDom = dom_import_simplexml($libSimple);
$dom = new DOMDocument();
// returns a copy of the node to import
$libDom = $dom->importNode($libDom, true);
// associate it with the current document.
$dom->appendChild($libDom);
fnDOMRearrange($num1,$num2,$dom); // see below DOM function
}
DOM :
// Exchange Position of 2nd book with 3rd : fnDOMRearrange(2,3);
function fnDOMRearrange($num1,$num2,$dom=0) {
if (!$dom) {
$dom = new DOMDocument();
$dom->load('library.xml');
}
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$cnt = $library->childNodes->length;
//echo '<br> count : ' . $cnt;
if ($num1 > $num2) { // ensure $num1 always is less than $num2
$num3 = $num1;
$num1 = $num2;
$num2 = $num3;
}
$index1 = fnDOMConvIndex($num1, $cnt);
$index2 = fnDOMConvIndex($num2, $cnt);
/*for ($iter = 0; $iter <= $cnt; $iter++) {
echo '<hr>' . $iter . '<br>' . $library->childNodes->item($iter)->nodeValue;
}*/
$library->childNodes->item(0)->parentNode->insertBefore($library->childNodes->item($index1), $library->childNodes->item($index2)); // put x before y
$library->childNodes->item(0)->parentNode->insertBefore($library->childNodes->item($index2), $library->childNodes->item($index1)); // put y before x
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
function fnDOMConvIndex($num, $cnt) {
// echo '<br>' . $num;
if ($num != 1) {
$maxIndex = floor($cnt/2);
//echo '<br>max: ' . $maxIndex;
if ($maxIndex == $num) {
$num = $cnt-2;
} else {
$num = ($num%2)?($num+2):($num+1); // Always odd index due to nature of DOM Element Index.
}
}
// echo '<br>' . $num;
return $num;
}
10. Display Required data in XML Form itself OR Remove all children nodes save one OR Copy/Clone Node Eg OR Compare/Search non numeric data (like date or time) to get result.
SimpleXML :
// Display Books published after 1980 in XML Form itself.
// No function to copy node directly in SimpleXML.
// Its simpler for this functionality to be implemented in DOM.
function fnSimpleXMLDisplayElementCond() {
$library = new SimpleXMLElement('library.xml',null,true);
$book = $library->xpath('/library/book[translate(@pubdate,"-","")>translate("1980-01-01","-","")]');
// Manually create a new structure then add searched data to it (see create xml eg.)
}
DOM :
// Display Books published after 1980 in XML Form itself.
function fnDOMDisplayElementCond() {
$dom = new DOMDocument();
$dom->load('library.xml');
$library = $dom->documentElement;
$xpath = new DOMXPath($dom);
// Comparing non numeric standard data
$result = $xpath->query('/library/book[translate(@pubdate,"-","")>translate("1980-01-01","-","")]');
// For simpler search paramater use this :
//$result = $xpath->query('/library/book[author="J.R.R.Tolkein"]');
// Copy only node & its attributes not its contents.
$library = $library->cloneNode(false);
// Add the 1 element which is search result.
$library->appendChild($result->item(0));
//header("Content-type: text/xml");
$dom->save('library_modified.xml');
}
Lessons Learned
- SimpleXML is fantastic for those who will only briefly flirt with XML (or beginners) & perform simple operations on XML.
- DOM is an absolute necessity for performing complex operations on XML data. Its learning curve is higher than SimpleXML off course but once you get the hang of it , you will know its very logical.
- Use XPath for conditional access to data. For serial access (like last book) XPath is not needed (but u can use it) since I can use normal DOM / SimpleXML node access.
