我需要一个递归的php函数来循环遍历xml文件

Question

I'm trying to loop through a xml file and save nodes pared with it's value into an array (key => value). I also want it to keep track of the nodes it passed (something like array(users_user_name => "myName", users_user_email => "myEmail") etc.).

I know how to do this but there is a problem. All the nodes could have children and those children might also have children etc. so I need some sort of recursive function to keep looping through the children until it reaches the last child.

So far I got this:

//loads the xml file and creates simpleXML object
        $xml = simplexml_load_string($content);

        // for each root value
        foreach ($xml->children() as $children) {
            // for each child of the root node
            $node = $children;
            while ($children->children()) {
                foreach ($children as $child) {

                    if($child->children()){
                        break;
                    }
                    $children = $node->getName();
                    //Give key a name
                    $keyOfValue = $xml->getName() . "_" . $children . "_" . $child->getName();
                    // pass value from child to children
                    $children = $child;

                    // no children, fill array: key => value
                    if ($child->children() == false) {
                        $parent[$keyOfValue] = (string)$child;
                    }
                }
            }
            $dataObject[] = $parent;
        }

The "break;" is to prevent it from giving me the wrong values because "child" is an object and not the last child.

Answer 1

Using recursion, you can write some 'complicated' processing, but the problem is loosing your place.

The function I use here passed in a couple of things to keep track of the name and the current output, but also the node it's currently working with. As you can see - the method checks if there are any child nodes and calls the function again to process each one of them.

$content = <<< XML
<users>
    <user>
        <name>myName</name>
        <email>myEmail</email>
        <address><line1>address1</line1><line2>address2</line2></address>
    </user>
</users>
XML;

function processNode ( $base, SimpleXMLElement $node, &$output )  {
    $base[] = $node->getName();
    $nodeName = implode("_", $base);
    $childNodes = $node->children();
    if ( count($childNodes) == 0 )  {
        $output[ $nodeName ] = (string)$node;
    }
    else    {
        foreach ( $childNodes as $newNode ) {
            processNode($base, $newNode, $output);
        }
    }
}

$xml = simplexml_load_string($content);
$output = [];
processNode([], $xml, $output);
print_r($output);

This prints out...

Array
(
    [users_user_name] => myName
    [users_user_email] => myEmail
    [users_user_address_line1] => address1
    [users_user_address_line2] => address2
)

With this implementation, there are limitations to the content - so for example - repeating content will only keep the last value (say for example there were multiple users).