php operation xml

Data to be manipulated

<?xml version="1.0"?>
<books>
    <book name="JavaScript: The Defiitive Guide" publisher="O&#39;Reilly Media, Inc.">
        <author>David Flanagan</author>
    </book>
    <book name="PHP anf MySQL Web Development" publisher="Perason Education">
        <author>Luke Welling</author>
        <author>Laura Thomson</author>
    </book>
    <book name="HTTP: The Defiitive Guide" publisher="O&#39;Reilly Media, Inc.">
        <author>David Courley</author>
        <author>Brian Totty</author>
    </book>
</books>

Several basic concepts of XML
1. Node: Node is the Node used in many programming languages ​​when processing XML. Node is a relatively broad concept, including elements, attributes, namespaces, and comments in XML. , text content, processing instructions, and the entire document belong to nodes, that is to say, each independent small part of the XML document is a node, is, So is name="XXXX", the tag is, and even the author's name David Flanagan is a text node.
2. Elements: Many programming languages ​​have XML processing. Node is a very broad concept. Because of the need to unify the API, there will not be too many methods for nodes. Elements are a subset of nodes. To put it simply It’s just tags like . Generally, there are many operation methods for elements.
3. Attributes: This is easier to understand. Things like XX="OO" in <> are all attribute nodes.
4. Escape characters: Similar to HTML, xml also has language-occupied symbols. If you want to use These special characters need to be escaped

DOMDocument object
I use the DOMDocument object to operate xml. I feel that it is more scientific than simpleXml. Of course, it is purely a personal feeling when using php on the first day. DOMDocument has several commonly used properties and methods.

Load xml

$path=$_SERVER["DOCUMENT_ROOT"].'/books.xml';
    $books=new DOMDocument();
    $books->load($path);

Read/traverse nodes and attributes

$bookElements=$books->getElementsByTagName('book');
    foreach($bookElements as $book){
        foreach ($book->attributes as $attr) {
            echo strtoupper($attr->nodeName).&#39; —— &#39;.$attr->nodeValue.&#39;<br/>&#39;;
        }
        echo "AUTHOR: ";
        foreach ($book->getElementsByTagName(&#39;author&#39;) as $author) {
            echo $author->nodeValue.&#39; &#39;;
        }
        echo &#39;<br/><br/>&#39;;
    }

Of course, for many attributes, if you only want to read one, you can read by index through the item(index) method

echo $book->attributes->item(1)->nodeValue;

You can also pass Powerful xpath query

还可以通过强大的xpath查询

Modify attributes/nodes

foreach($bookElements as $book){
        foreach ($book->attributes as $attr) {
            #$book->setAttribute($attr->nodeName,strtoupper($attr->nodeValue));
            $attr->nodeValue=strtoupper($attr->nodeValue);
        }
        echo "AUTHOR: ";
        foreach ($book->getElementsByTagName('author') as $author) {
            $author->nodeValue=strtoupper($author->nodeValue);
        }
    }
    $books->save($path);

For attribute modifications, you can directly access its nodeValue changes, or you can use the setAttribute method. Don’t forget to use save after making changes.

$book->setAttribute($attr->nodeName,strtoupper($attr->nodeValue));
$attr->nodeValue=strtoupper($attr->nodeValue);

Add elements/attributes

$newBook=$books->createElement('book'); #创建新元素
    $newBook->setAttribute('name','PHP Objects, Patterns, and Practice');#创建新属性，方法一
    $publisher=$books->createAttribute('publisher');#创建新属性，方法二
    $publisher->nodeValue='Apress L.P';
    $newBook->appendChild($publisher); #把属性添加到元素上
    $author=$books->createElement('author');#创建子元素
    $author->nodeValue='Matt Zandstra';
    $newBook->appendChild($author);#把子元素添加到父元素上
    $books->documentElement->appendChild($newBook);#添加整个节点
    $books->save($path);

Delete attributes/nodes

$first=$bookElements->item(0);
    $first->removeAttribute('publisher');
    $second=$bookElements->item(1);
    $second->parentNode->removeChild($second);
    $books->save($path);

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