PHP DomDocument Tutorial

Table of content

• Load Document
• Loop Through XML
• Retrieve Specific Element
• Conclusion

This will be a quick tutorial that will show you how to use PHP’s DOMDocument to parse your XML so you do not have to use XML parser. In this tutorial you’ll see how to loop through your XML file and how to extract some specific data. For this, we will use XML file that is available on w3schools.com.

Load DocumentTop

First thing we have to do is to make an instance of DOMDocument class.

$dom = new DOMDocument();

Now that we have instance, we can load document. To do that we’ll use load method. As an argument we pass path to our XML file.

$dom->load('http://www.w3schools.com/XML/simple.xml');

Now our document is loaded and we can do with it what we want.

Loop Through XMLTop

Now we will loop through our XML file. Let’s say we want to print data from food elements. To do that we have to select them first. We’ll do that by using getElementsByTagName method and pass name of our element (food).

$food = $dom->getElementsByTagName('food');

If you do var_dump on $food variable you’ll see that you get instance of DOMNodeList class. It has method item and variable $length so you can loop through them or use foreach to do the job. When you loop you’ll get each element that you got from your query as DOMElement and then you can do new queries or modify that element. We’ll just loop.

<ul>
< ?php
//Loop through each item
foreach ($food as $elem) {
?>
    <li>
        <table>
            <tbody>
                <tr>
                    <td><b>Name:</b></td>
                    <td>< ?php echo $elem->getElementsByTagName('name')
                                        ->item(0)
                                        ->nodeValue; ?></td>
                </tr>
                <tr>
                    <td><b>Description:</b></td>
                    <td>< ?php echo $elem->getElementsByTagName('description')
                                        ->item(0)
                                        ->nodeValue; ?></td>
                </tr>
                <tr>
                    <td><b>Price:</b></td>
                    <td>< ?php echo $elem->getElementsByTagName('price')
                                        ->item(0)
                                        ->nodeValue; ?></td>
                </tr>
                <tr>
                    <td><b>Calories:</b></td>
                    <td>< ?php echo $elem->getElementsByTagName('calories')
                                        ->item(0)
                                        ->nodeValue; ?></td>
                </tr>
            </tbody>
        </table>
    </li>
< ?php
}
?>
</ul>

As you can see, we do new queries on our element retrieved from loop. We want element with tag names name, description, price and calories. When we get our element we want first of them that is in list of elements retrieved from query and it’s value. This is how we loop through our XML. Result should be something like this.

• Name:	Belgian Waffles
  Description:	two of our famous Belgian Waffles with plenty of real maple syrup
  Price:	$5.95
  Calories:	650

• Name:	Strawberry Belgian Waffles
  Description:	light Belgian waffles covered with strawberries and whipped cream
  Price:	$7.95
  Calories:	900

• Name:	Berry-Berry Belgian Waffles
  Description:	light Belgian waffles covered with an assortment of fresh berries and whipped cream
  Price:	$8.95
  Calories:	900

• Name:	French Toast
  Description:	thick slices made from our homemade sourdough bread
  Price:	$4.50
  Calories:	600

• Name:	Homestyle Breakfast
  Description:	two eggs, bacon or sausage, toast, and our ever-popular hash browns
  Price:	$6.95
  Calories:	950

Retrieve Specific ElementTop

Let’s say we want to get value of name element in third food element and print it out. We will use something like this.

$third = $dom->getElementsByTagName('food')
             ->item(2);
echo sprintf(
    'Name of third element is: <b>%s</b>',
    $third->getElementsByTagName('name')
          ->item(0)
          ->nodeValue
);

You should get result like this.

Name of third element is: Berry-Berry Belgian Waffles

ConclusionTop

DOM classes in PHP are very powerful and I like to use them for parsing XML much more then XML parser because they are build in object-oriented way and can be very easy extended. Thank you for reading.

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