PHP and XML - Create, Add, Edit, Modify using DOM , SimpleXML

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:

(1) Create XML OR Array to XML Conversion OR CDATA Element Eg

(2) Edit XML – Edit/Modify Element Data (accessed serially)

(3) Edit XML – Edit specific Elements (accessed conditionally)

(4) Edit XML – Element Addition (to queue end)

(5) Edit XML – Element Addition (to queue start)

(6) Edit XML – Element Addition (before a specific node)

(7) Delete Elements (accessed serially)

(8) Delete Elements (accessed conditionally)

(9) Rearrange / Reorder Elements

(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.

library.xml will be used in all operations.

ps : I have added the indention & spaces outside the tags in the below xml for a presentable xml form.

Remove them before saving your xml file else most of the usual XML functions wont work in the desired manner.

<?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 Eg

#######################################

// (i) 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']);
        }

        $library->asXML('library.xml');
    }

// (ii) 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)

#######################################

// (i) 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();
    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

// (3) Edit XML – Edit specific Elements (accessed conditionally)

#######################################

// (i) 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();
    }

// (ii) DOM (with XPath):

 //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");
        echo $dom->saveXML();

    }

#######################################

// (4) Edit XML – Element Addition (to queue end)

#######################################

// (i) 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();
    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

//(5) Edit XML – Element Addition (to queue start)

#######################################

// (i) 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
    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

// (6) Edit XML – Element Addition (before a specific node)

#######################################

// (i) 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.
    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

// (7) Delete Elements (accessed serially)

#######################################

// (i) 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();

    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

// (8) Delete Elements (accessed conditionally)

#######################################

// (i) 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();

    }

// (ii) 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");
        echo $dom->saveXML();
    }

#######################################

// (9) Rearrange / Reorder Elements

#######################################

// (i) SimpleXML :

 // Exchange Position of 2nd book with 3rd.
// 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()
    {
         $library = new SimpleXMLElement('library.xml',null,true);
         //$library->book[3] = $library->book[0]; // this doesnt work

         $cnt = count($library);
         // Custom function which basically uses a 3rd container to exchange nodes data.
         fnNodeExchange($library,2,1);
         //$library->book[2] = $temp;
         header("Content-type: text/xml");
        echo $library->asXML();
    }
function fnNodeExchange(&$library,$node1,$node2)
    {
        $cnt = count($library);

        foreach($library->book[$node1]->children() as $book)
         {
            $name = $book->getName();
            $library->book[$cnt]->$name = $book[0];
         }
         foreach($library->book[$node1]->attributes() as $book)
         {
            $name = $book->getName();
            $library->book[$cnt][$name] = $book[0];
         }
         foreach($library->book[$node2]->children() as $book)
         {
            $name = $book->getName();
            $library->book[$node1]->$name = $book[0];
         }
         foreach($library->book[$node2]->attributes() as $book)
         {
            $name = $book->getName();
            $library->book[$node1][$name] = $book[0];
         }
         if($node2!=($cnt-1)){
            foreach($library->book[$cnt]->children() as $book)
            {
               $name = $book->getName();
               $library->book[$node2]->$name = $book[0];
            }
            foreach($library->book[$cnt]->attributes() as $book)
            {
               $name = $book->getName();
               $library->book[$node2][$name] = $book[0];
            }
            unset($library->book[$cnt]);
         }
         else {
            unset($library->book[$cnt-1]);
         }
    }

// (ii) DOM :

// Exchange Position of 2nd book with 3rd.
    function fnDOMRearrange()
    {
        $dom = new DOMDocument();
        $dom->load('library.xml');
        $library = $dom->documentElement;
        $library->childNodes->item(0)->parentNode->insertBefore($library->childNodes->item(2),$library->childNodes->item(1));
        header("Content-type: text/xml");
        echo $dom->saveXML();
    }

#######################################

// (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.

#######################################

// (i) 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.)
    }

// (ii) 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");
        echo $dom->saveXML($library);
    }

---

Lessons Learn’t :

• 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.

---